Stent for the positioning and anchoring of a valvular prosthesis in an implantation site in the heart of a patient

ABSTRACT

A method of placing an implant including a stent at a native heart valve site includes orienting an expandable body of the stent such that a first open end of the stent is upstream a second open end of the stent relative to a direction of blood flow through a native heart valve. The native heart valve includes native leaflets and an annulus. The method also includes radially expanding a plurality of positioning arches positioned around an outer perimeter of the expandable body. The method additionally includes inserting the plurality of positioning arches respectively within a plurality of pockets defined by leaflets of the native heart valve and a heart structure from which the native leaflets extend. The method further includes radially expanding the first open end of the stent into a position upstream of the annulus and out of contact with nerve bundles.

This application is a continuation of U.S. patent application Ser. No.15/266,295, filed Sep. 15, 2016, which is a continuation of U.S. patentapplication Ser. No. 15/221,860, filed Jul. 28, 2016 (now U.S. Pat. No.9,987,113), which is a continuation of U.S. patent application Ser. No.14/312,180, filed Jun. 23, 2014 (now U.S. Pat. No. 9,439,759), which isa continuation of U.S. patent application Ser. No. 13/896,905, filed May17, 2013 (now U.S. Pat. No. 8,790,395), which is a continuation of U.S.patent application Ser. No. 13/033,023, filed Feb. 23, 2011 (now U.S.Pat. No. 8,465,540), which is a continuation-in-part of U.S. patentapplication Ser. No. 12/713,058, filed Feb. 25, 2010 (now U.S. Pat. No.8,398,704), which is a continuation-in-part of U.S. patent applicationSer. No. 12/392,467, filed Feb. 25, 2009 (now U.S. Pat. No. 8,317,858),which is a continuation-in-part of U.S. patent application Ser. No.12/285,544, filed Oct. 8, 2008 (now U.S. Pat. No. 9,168,130), which is acontinuation-in-part of U.S. patent application Ser. No. 12/071,814,filed Feb. 26, 2008 (now U.S. Pat. No. 9,044,318), each of which isincorporated herein by reference in its entirety.

DESCRIPTION

The present invention relates to a stent for the positioning andanchoring of an endoprosthesis in an implantation site in the heart of apatient. Specifically, the present invention relates to an expandablestent for an endoprosthesis used in the treatment of a stenosis(narrowing) of a cardiac valve and/or a cardiac valve insufficiency.

The present invention also relates to an endoprosthesis that includes astent for positioning and anchoring of the prosthesis at theimplantation site in the heart of a patient. Specifically, the presentinvention also relates to a collapsible and expandable prosthesisincorporating a stent that can be delivered to the implant site using acatheter for treatment of a stenosis (narrowing) of a cardiac valveand/or a cardiac valve insufficiency.

The expression “narrowing (stenosis) of a cardiac valve and/or cardiacvalve insufficiency” is intended to include a functional defect of oneor more cardiac valves, which is either genetic or has developed. Acardiac defect of this type might affect each of the four heart valves,although the valves in the left ventricle (aortic and mitral valves) areaffected much more often than the right-sided part of the heart(pulmonary and tricuspid valves). The functional defect can result innarrowing (stenosis), inability to close (insufficiency) or acombination of the two (combined vitium). This invention relates to anendoprosthesis that includes an expandable stent capable of beingimplanted transluminally in a patient's body and enlarged radially afterbeing introduced percutaneously for treating such a heart valve defect.

In the current treatment of severe narrowing of a cardiac valve and/orcardiac valve insufficiency, the narrowed or diseased cardiac valve isreplaced with an endoprosthesis. Biological or mechanical valves models,which are typically surgically sewn into the cardiac valve bed throughan opening in the chest after removal of the diseased cardiac valve, areused for this purpose. This operation necessitates the use of aheart-lung machine to maintain the patient's circulation during theprocedure and cardiac arrest is induced during implantation of theprosthesis. This is a risky surgical procedure with associated dangersfor the patient, as well as a long post-operative treatment and recoveryphase. Such an operation can often not be considered with justifiablerisk in the case of polypathic patients.

Minimally-invasive forms of treatment have been developed recently whichare characterized by allowing the procedure to be performed under localanesthesia. One approach provides for the use of a catheter system toimplant a self-expandable stent to which is connected a collapsiblevalvular prosthesis. Such a self-expandable endoprosthesis can be guidedvia a catheter system to the implantation site within the heart throughan inguinal artery or vein. After reaching the implantation site, thestent can then be unfolded.

To this end, it is known that a stent may be comprised of, for example,a plurality of self-expanding longitudinal stent segments, the segmentsbeing articulated relative to one another. In order to anchor the stentsecurely in position in an appropriate blood vessel close to the heart,anchoring barbs are frequently used to engage with the vascular wall.

An expandable stent for the fastening and anchoring of an endoprosthesisis known from printed publication DE 10 010 074 A1, whereby the stent isessentially formed from wire-shaped, interconnected segments. DE 10 010074 A1 proposes a stent for fastening and anchoring an endoprosthesis,the stent having different arched elements which assume the function offastening and supporting the valvular prosthesis at the site ofimplantation. Specifically, three identically-configured positioningarches spaced 120° from one another respectively are used. Thesepositioning arches are connected to one another by means of solid bodyarticulations. In addition to the positioning arches, complementarycurved retaining arches serve to anchor the endoprosthesis by pressingradially against the vascular wall following the unfolding of the stent.

However, there is a risk of inexact or incorrect implantation of anendoprosthesis using the solutions described above. Expressed in anotherway, there is a need for exact positioning and longitudinal alignment ofan implanted endoprosthesis. In particular, it is only possible usinggreat skill on the part of the attending surgeon or cardiologist—if atall—to position a stent sufficiently precisely, in both a lateral andlongitudinal direction, to ensure that the associated endoprosthesis islocated in the correct area of the patient's diseased heart valve.

Among other things, inexact implantation of a sub-optimally positionedendoprosthesis can lead to leakage or valvular insufficiency whichresults in considerable ventricular stress. For example, if anendoprosthesis is implanted too far above the plane of the native heartvalve, this can lead to closure or blocking of the coronary artery ostia(inlet orifice of coronaries) and thus to fatal coronary ischemia andmyocardial infarction.

Therefore, for the optimal treatment of a narrowed cardiac valve or acardiac valve insufficiency, it is necessary to position a stent, towhich a valvular prosthesis is affixed, as precisely as possible at thesite of implantation of the cardiac valve to be treated.

An endoprosthesis for treating aortic valve insufficiency is known fromprinted publication DE 20 2007 005 491 U1. The endoprosthesis comprisesa valvular prosthesis and a stent to position and anchor theendoprosthesis at the implantation site in the patient's heart. A stenthaving several (multiple, normally three, but two in case of bicuspidvalve) positioning arches is employed in this endoprosthesis. In theimplanted state of the stent, these positioning arches extend radiallyand serve to engage in the pockets of the native (diseased) cardiacvalve to be treated. The valvular prosthesis affixed to the stent canthen self-position into the plane of the cardiac valve. Retaining archesabut against the vascular wall of the aorta in the implanted state ofthe endoprosthesis, form a force-fit connection and are used to anchorthe endoprosthesis.

While the positioning arches enable optimal positioning of the stent ofthis endoprosthesis at the site of implantation in the patient's heart,what cannot be ensured is that the valvular prosthesis attached to thelower end section of the stent is actually also positioned in the planeof the cardiac valve. In particular, substantial forces act on theendoprosthesis during the filling phase of the heart cycle (diastole),which can lead to the endoprosthesis displacing longitudinally relativethe stent. Due to this longitudinal displacement of the implantedendoprosthesis, which occurs in the heart and blood vessels especiallybecause of the peristaltic motion of the heart, the implantedendoprosthesis may no longer be able to provide a secure seal.

Moreover, there is the danger that, because of the longitudinaldisplacement of the valvular prosthesis relative to the stent occurringwith the peristaltic motion, the threads or sutures used to fasten thevalvular prosthesis to the stent may chafe against the stent. It cantherefore not be excluded that the fastening threads may fray over thecourse of time and thus lose their fastening function. This would resultin at least a partial separation of the valvular prosthesis from thestent, which in turn can lead to leakages, an inappropriate positioningor even complete detachment of the valvular prosthesis.

On the basis of the problems outlined above, certain embodiments of thepresent invention address the issue of providing a self-expandableendoprosthesis for treating a narrowed cardiac valve or a cardiac valveinsufficiency which realizes optimum positioning accuracy and anchoringof an endoprosthesis to be implanted. In addition, the treatment of thenarrowed cardiac valve or cardiac valve insufficiency should be by wayof a simple procedure to enable routine treatment of narrowed cardiacvalve or cardiac valve insufficiency without major stress to thepatient.

In this regard and as it will be described later in detail, theinvention provides an expandable stent for the positioning and anchoringof an endoprosthesis in an implantation site in the heart of a patientin the treatment of a narrowed cardiac valve or a cardiac valveinsufficiency, wherein the stent comprises a plurality of positioningarches configured to be positioned within a plurality of pockets of thepatient's native heart valve and positioned on a first side of aplurality of native heart valve leaflets, and a plurality of retainingarches configured to be positioned on a second side of the plurality ofnative heart valve leaflets opposite the first side.

As it will be described in detail later on, in some embodiments of thepresent invention, the expandable stent may further include at least oneauxiliary arch interspaced between two adjacent retaining arches,wherein the at least one auxiliary arch includes a first arm connectedat a first end thereof to a first retaining arch and a second armconnected at a first end thereof to a second retaining arch, and whereinthe first and second arms of the at least one auxiliary arch eachinclude respective second ends connected to one another at a joint thatincludes at least one fastening hole configured to receive a suture.

In addition or instead of the at least one auxiliary arch, the stentaccording to the present invention may further comprise at least oneradial arch substantially circumferentially aligned with at least one ofthe plurality of positioning arches.

Otherwise, it is conceivable that the stent according to the presentinvention is further provided with a plurality of auxiliary arches, eachof said plurality of auxiliary arches being interspaced between twoadjacent retaining arches and including a first arm connected at a firstend thereof to a first retaining arch and a second arm connected at afirst end thereof to a second retaining arch.

Furthermore, the stent according to the present invention may also beprovided with a plurality of extra arches, each of said plurality ofextra arches being interspaced between a first retaining arch and anadjacent second retaining arch.

Preferably, the stent according to the present invention furthercomprises a plurality of leaflet guard arches, each interspaced betweenthe two arms of one of the plurality of positioning arches.

A further task of certain embodiments of the present invention lies inspecifying an endoprosthesis for the treatment of a stenosed cardiacvalve or a cardiac valve insufficiency, whereby the endoprosthesis canbe anchored securely at the site of implantation in the patient's heart.In addition, certain embodiments of the present invention also addressthe issue of substantially preventing displacement of an implantedendoprosthesis from its ideal site of implantation in spite of theforces acting on the endoprosthesis during the filling phase of theheart cycle.

The present invention is also directed to an endoprosthesis constitutedby a stent as defined in the claims on the one hand and a valvularprosthesis affixed to the stent.

As described herein, stents may be radially expandable intravascularimplants capable of being implanted transluminally and enlarged radiallyafter being introduced percutaneously. The stents may be configured tobe placed in a native diseased valve of a patient, such as a nativestenotic aortic or pulmonary valve, using a minimally-invasive approach,such as a beating heart transapical procedure or a retrogradetransaortic procedure. Although stents can be introduced into the bodyof the patient via any number of access points, a transvascular approachby femoral access or by transapical access for the aortic valve ispreferred. However, this invention is not limited to these approaches.

A “native aortic valve” may be a tricuspid (with three leaflets) orcongenitally bicuspid (with two leaflets).

An endoprosthesis may include an implant which (together with a stent towhich the valvular prosthesis is affixed) functions as a check valve,opening to permit forward blood flow and closing to prevent retrogradeflow. A valvular prosthesis may consists of at least two and preferablyof three leaflets and a valve skirt on which the leaflets are connected.

From one aspect, an expandable stent of a collapsible and expandableprosthesis is proposed in accordance with certain embodiments of thepresent invention, the stent comprising at least one fastening portionby means of which a valvular prosthesis is connected to the stent. Inaddition, the stent comprises positioning arches and retaining arches.At least one positioning arch of the stent is connected with at leastone retaining arch of the stent by a first connecting web. Additionally,the stent further comprises at least one auxiliary arch whichinterconnects the arms of respective retaining arches.

The at least one fastening portion extends along the longitudinal axisof the stent and comprises a plurality of fastening holes distributed ina longitudinal direction at discrete positions along the length of theat least one fastening portion. Thread or thin wire may be guidedthrough each fastening hole to secure the valvular prosthesis to thestent. The advantage of this feature is that longitudinal displacementof the valvular relative to the stent is substantially minimized onceimplanted and so the prosthesis is not unduly disturbed or weakened as aresult of the heart's peristaltic motion.

In addition to fastening holes, the fastening portion may include one ormore notches to assist the seating and retaining of suture material. Thenotches also assist with even attachment of the prosthesis to the stentand, similarly to the fastening holes, minimize longitudinaldisplacement of the prosthesis.

Extending from and between a pair of fastening portions is a fasteningarch, over which valve tissue is laid. In the expanded and implantedstate of the stent and the valvular prosthesis affixed thereto, thefastening arch of the stent abuts against the vessel wall at least atthe lower section of the stent in order to seal against leakage.Furthermore, with the fastening arch, the prosthesis tissue is separatedand held away from positioning and retaining arches, thereby reducingthe likelihood of these arches chaffing the tissue which, in turn mayresult in damage and weakening of the prosthesis. The fastening archserves to anchor the lower edge of the valvular prosthesis and totension the material so the prosthesis is effective as a valve. Byhaving a fastening portion and fastening arches, the prosthesis is fullysupported and anchored within the boundary of the stent. The combinationof the two fastening mechanisms also provides a failsafe should onefastening mechanism fail. This is of particular relevance with suturingsince a poorly sutured prosthesis will not be as effective as it shoulddue to additional stresses and strains imparted to the prosthesis by thesutures. Thus, the arches allow fastening of the prosthesis in a mannerthat does not rely solely on suturing.

In an implanted configuration, the at least one positioning arches ofthe stent extends from the circumference of the stent in a generallyradial direction. These positioning arches are designed to engage in thepockets of the native (diseased) cardiac valve that is being replacedwhich, in turn allows accurate positioning of the stent. Furthermore, onimplantation, a positioning arch sits between the vascular wall and aleaflet of the native heart valve. The positioning arch then co-operateswith a corresponding retaining arch resulting in clipping of the nativeleaflet between the two arches. In this way, the positioning andretaining arches together hold the stent in position and substantiallyeliminate axial rotation of the stent.

In a preferred embodiment (cf. the stent according to the eighteenthembodiment), the positioning arch may be shaped to have a substantiallyconvex shape. In other words, the end of the arch that is positioned inthe native valve leaflet may be curved towards the inside of the stentor towards the longitudinal axis of the stent. In this way, the shape ofthe each positioning arch provides an additional clipping force againstthe native valve leaflet.

The at least one retaining arch is connected to a positioning arch by aconnecting web. The retaining arch extends radially in the implantedstate of the stent such that the at least one retaining arch pressesagainst the wall of the blood vessel in which the stent is deployed witha radially-acting tensioning force. In situ, the ends of each retainingarch also fits underneath the aortic valve annulus, providing furthermeans for locating and anchoring the stent. In addition to the at leastone retaining arch, certain embodiments of the invention provide for thestent to further comprise at least one auxiliary arch whichinterconnects the respective arms of the at least one retaining archconnected to the at least one positioning arch. As with the at least oneretaining arch, the at least one auxiliary arch also protrudes radiallyin the expanded state of the stent such that the at least one auxiliaryarch also presses against the wall of the blood vessel in which thestent is deployed with a radially-acting tensioning force.

The stent of a collapsible and expandable prosthesis may also includeradial arches positioned between each positioning arch, with each radialarch extending upwards towards the upper end section of the stent. Theradial arches provide additional means by which the stent may beretained within a catheter before and during implantation, and providemeans by which the stent may be recaptured after implantation. Thearches also add radial strength to the upper end section of the stent.

In the at least one fastening portion of the stent, by means of whichthe tissue component(s) of the overall prosthesis can be fastened to thestent, a plurality of fastening holes and optionally one or more notchesis provided. These fastening holes and notches are longitudinallydistributed at given positions on the fastening portion and guide atleast one thread or thin wire to fasten the tissue component(s) of thevalvular prosthesis to the stent, thereby enabling a precise positioningof the tissue component(s) of the overall prosthesis on the stent. Eachindividual fastening hole and notch provided in the at least onefastening portion thereby serves to guide a thread or thin wire withwhich the tissue component(s) of the valvular prosthesis is affixed orsewn to the fastening portion of the stent.

The means provided for fastening the tissue component(s) of the valvularprosthesis to the fastening portion of the stent (thread or thin wire)is guided by way of the fastening holes and notches so that alongitudinal displacement of the valvular prosthesis relative to thestent is substantially minimized. This also allows exact positioning ofthe valvular prosthesis relative the stent.

The secure and defined fixing of the tissue component(s) of the valvularprosthesis to the at least one fastening portion of the stent moreovereffectively prevents the means used to fasten the tissue component(s) tothe stent. (threads or thin wires) from rubbing against the stent andthus degrading after a longer period of use.

In order to configure the plurality of fastening holes and any notchesin the fastening portion, the at least one fastening portion ispreferably configured as—in comparison to the respective arms of thepositioning arch, retaining arch and auxiliary retaining arch—a widenedsegment. Thus, the fastening portion is a stent segment which comprisesa relatively large amount of material, facilitating movement andposition analysis when the stent is being implanted. For example, whenfluoroscopy (cardiac catheterization=LHK) or ultrasound(trans-esophageal echocardiogram=TEE) is used to monitor the insertionprocedure, the fastening portion of the stent is particularlydistinguishable.

A preferred realization of the stent according to a particularembodiment the invention provides for a fastening portion to beconfigured within each arm of the stent's retaining arch.

In order to reinforce the respective retaining arches of the stent, theauxiliary arch as already mentioned above is provided. The auxiliaryarch extends from the lower ends of the fastening portion and connectsthe respective arms of two neighboring retaining arches.

In manufacturing the stent used in the valvular prosthesis according toa particular embodiment of the invention, it is conceivable for thestent to exhibit a structure integrally cut from a portion of tube, inparticular from a metal tube, which incorporates the positioning arches,retaining arches and auxiliary retaining arches as well as the at leastone fastening portion with defined fastening holes and notches. It isalso conceivable that the stent is cut out of a relatively large tube,i.e. a tube having a diameter which is larger compared with the diameterof the final stent in its collapsed configuration. For example, a tubehaving a diameter of approximately 10 mm may be used for cutting aspecific stent pattern into this tube. Then the cut pattern will bedifferent, as it will become necessary to crimp the stent to somethingsmaller than what it was originally cut from. In particular, with thisprocedure it is possible to remove material during cutting andprocessing in a defined manner thereby enhancing the functionality ofthe final stent.

Specifically, it is conceivable to use a laser to cut the stentstructure from a metal tube, whereby the structure is thereafter subjectto an applicable shaping and thermal treatment process so that the stentcan transform from a collapsed state during implantation into anexpanded state at the site of implantation. This shaping and thermaltreatment process is advantageously performed gradually in order toprevent damage to the stent structure.

Particularly preferred is for the stent to exhibit a structureintegrally cut from a metal tube in which each positioning arch isallocated one retaining arch, and in which each upper end portion of thepositioning arch towards the upper end of the stent is connected withthe upper end portion of the associated retaining arch via a firstconnecting web. The at least one fastening portion, in which theplurality of fastening holes is provided, is thereby preferablyconfigured within an arm of the retaining arch.

The stent preferably exhibits an integrally-formed structure which cantransform from a first predefinable shape into a second predefinableshape, whereby the stent exhibits a first predefinable shape (collapsedshape) during insertion into the patient's body and a secondpredefinable shape (expanded shape) once implanted. Because of thestent's design, during the transition of the stent from the firstpredefinable shape into the second predefinable shape, the positioningarches, retaining arches and auxiliary arches are radially expanded as afunction of the cross-sectional expansion of the stent. The stent'ssecond shape is thereby preferably selected such that when the stent isexpanded, the retaining arch and the auxiliary arch abut against thewall of the blood vessel in which the stent is deployed. In addition,the ends of the retaining arches are positioned beneath the native valveannulus, thereby providing additional anchoring of the stent.

To achieve a secure anchoring of the stent at the site of implantation,both the retaining and auxiliary arches should press against the wall ofthe vessel with a radial force, whereby this radial force can be set bysubjecting the stent structure to a suitable shaping and thermaltreatment process.

It is to be understood that the term “upper” refers to the stent whenviewed in its implanted state. In other words, the term “upper” refersto the upper end section of the stent which, when implanted, is sitedaway from the heart. Similarly, use of the term “lower” refers to aproximal position on the stent which is located towards the ventricleside of the heart when the stent is viewed in its implanted position.

A preferred embodiment (cf. the eighteenth embodiment) of the stentaccording to the invention provides for the positioning arches and theassociated retaining arches as well as auxiliary arches each to exhibitan essentially U-shaped, T-shaped or V-shaped structure which is closedtoward the lower end of the stent. It is particularly preferred for eachpositioning arch to be cut from the material portion of a metal tubefrom which the essentially U-shaped, T-shaped or V-shaped structure ofthe associated retaining arch was taken. The respective auxiliary archesare preferably cut from a material portion of the metal tube situatedbetween the essentially U-shaped, T-shaped or V-shaped retaining archstructures.

This preferred embodiment of the stent structure thus provides for therespective retaining and auxiliary arches of the stent to form the lowerregion of the endoprosthesis, whereby the positioning arches areconfigured symmetrically to the retaining arches although preferablydisposed somewhat further toward the upper region of the endoprosthesis.

The respective upper ends of the positioning arches are connected to therespective upper ends of the associated retaining arches by means of afirst connecting web in the upper region of the endoprosthesis. Thefastening portions are configured in the respective arms of theretaining arch. In the expanded state of the stent, both the lowerregion with the fastening portions, as well as the connecting webdisposed at the upper end of the stent between the respectivepositioning and retaining arches, spread out so that a radially-actingforce is exerted on the blood vessel wall from both the lower region ofthe stent as well as the upper end of the stent, thereby enabling secureanchoring of the stent at the site of implantation.

In a preferred embodiment, the stent exhibits in its first shape(collapsed shape) an outer diameter of approximately 4 to 8 mm and alength of between 30 mm and 42 mm. More precisely, the stent may exhibitin its first shape (collapsed shape) an outer diameter of approximately4.0 to 8.0 mm, preferably of approximately 5.0 mm, more preferably ofapproximately 6.0 mm, and a length of between 33.0 mm and 40.0 mm,preferably between 34.0 mm and 40.0 mm, and more preferably between 34.0mm and 39.0 mm. This allows a prosthesis including the stent to beinserted easily into the patient's body, for example with a 21 Fdelivery system, and to be used with an endoprosthesis having a diameterof between 19 mm and 28 mm. The afore-mentioned length specificationsare the dimensions currently preferred, based on which the stent becomessuitable for the majority of patients to be treated.

In order to achieve a particularly secure anchoring of the implanted thestent with the stretched valvular prosthesis affixed thereto, it isfurther conceivable for the stent to be subject to a shaping and thermaltreatment process during its manufacture such that the finished stentexhibits a slightly concave configuration.

For example, the finished stent may exhibit a slightly concaveconfiguration tapering toward its upper end section in its implanted andfully expanded state. When the stent together with a valvular prosthesisaffixed thereto is in its implanted and fully expanded state, thelargest diameter of the lower end section of the stent is positionedbelow the annulus and tries to assume a larger diameter than the upperend section of the stent even though the upper end section of the stentspreads out a little larger, thereby providing larger radial forces toanchor the stent and the valvular prosthesis affixed thereto in theimplanted state. This enables a secure hold of the stent in the bloodvessel without damaging the arterial wall. This configuration alsoprovides secure anchoring that is able to withstand the peristalticmotion of the heart and the arterial wall and reliably seal theprosthesis against the arterial wall. It is of course also conceivableto design the concave configuration of the stent in its second shape tobe of greater or lesser concavity.

Preferably, the stent diameter at the lower end section of the stentshould be able to accommodate a range of annulus diameters around thetarget diameter. Within this range the forces applied due to thestiffness of the expanded and implanted stent to the vessel wall shallbe adequate to prevent migration of the implanted stent, but not toogreat to cause annular rupture or AV node block. At the upper endsection of the stent, it is desirable that the stent does not vary indiameter significantly to minimize the impact to the valve coaptation oropening performance even when the annulus diameter is not exactly at thetarget diameter.

It is preferable for the lower end area of the stent, when in its secondshape, to exhibit a diameter of between 22 mm and 33 mm, preferablybetween 25 mm and 31 mm. It is conceivable for the stent to exhibit twoor more differently dimensioned sizes whereby the optimal stent size canbe selected depending upon specific patient. In addition, exact andpatient-specific dimensions of the stent—starting from a given stentsize—can be realized by appropriately curing the stent, in particular bya thermal treatment process.

In a particularly preferred realization, the stent comprises a valvularprosthesis, preferably a biological or pericardial valvular prosthesis,wherein the tissue component(s) of the valvular prosthesis is/areattached to the at least one fastening portion of the stent by means ofa thread or the like.

A shape memory material is preferably used as the material for thestent, the material being designed such that the stent can transformfrom a temporary shape into a permanent shape under the influence of anexternal stimulus. The temporary shape is thereby the stent's firstshape (i.e. the collapsed state of the stent), while the permanent shapeis assumed in the stent's second shape (i.e. in the expanded state ofthe stent). In particular, use of a shape memory material such asNitinol, i.e. an equiatomic alloy of nickel and titanium, allows for aparticularly gentle implantation procedure when implanting the stent.

It is conceivable of course that other shape memory materials, forexample shape-memory polymers, are used as the material for the stent.At least parts of the stent may be formed by using, for example, apolymer composite exhibiting a crystalline or semi-crystalline polymernetwork having crystalline switching segments. On the other hand, anamorphous polymer network having amorphous switching segments is alsoconceivable.

When manufacturing the stent preferably made from a shape memorymaterial, the stent structure is preferably shaped after it has been cutfrom a tube. It is conceivable that the stent is cut out of a tubehaving a diameter which is larger compared with the diameter of thefinal stent in its collapsed configuration. Then, the laser-processedtube is crimped thereby achieving the diameter of the stent in itscollapsed configuration. Once the desired shape has been formed, thisshape is “fixed”, this process being known as “programming”, Programmingmay be effected by heating the stent structure, forming the stent intothe desired shape and then cooling the stent. Programming may also beeffected by forming and shaping the stent structure at lowertemperature, this being known as “cold stretching.” The permanent shapeis thus saved, enabling the stent to be stored and implanted in atemporary, non-formed shape. If an external stimulus then acts on thestent structure, the shape memory effect is activated and the saved,permanent shape restored.

A particularly preferred embodiment provides for the external stimulusto be a definable switching temperature. It is thus conceivable that thestent material needs to be heated to a higher temperature than theswitching temperature in order to activate the shape memory effect andthus regenerate the saved permanent shape of the stent. A specificswitching temperature can be preset by the relevant selection of thechemical composition of the shape memory material.

It is particularly preferred to set the switching temperature to be inthe range of between 10° C. and the patient's body temperature andpreferably in the range of between 10° C. and room temperature. Doing sois of advantage, especially with regard to the medical device being usedas an implant in a patient's body. Accordingly, all that needs to beensured in this regard when implanting the stent is that the stent iswarmed up to room temperature or the patient's body temperature (37° C.)at the site of implantation to activate the shape memory effect of thestent material.

The following will make reference to the included drawings in describingpreferred embodiments of the stent according to the present invention ingreater detail.

Shown are:

FIG. 1a a side view of a cardiac valve stent capable of supporting andanchoring an endoprosthesis in accordance with a first embodiment of theinvention, where the cardiac valve stent is shown in its collapsedstate;

FIG. 1b a side view of a cardiac valve stent capable of supporting andanchoring an endoprosthesis in accordance with the first embodiment ofthe invention, where the cardiac valve stent is shown in its expandedstate;

FIG. 1c a plan view of the lower end of a cardiac valve stent inaccordance with the first embodiment of the invention, where the cardiacvalve stent is shown in its expanded state;

FIG. 1d a side view of an endoprosthesis for treating a narrowed cardiacvalve or a cardiac valve insufficiency, where the endoprosthesiscomprises a cardiac valve stent according to the first embodiment of theinvention for holding an endoprosthesis;

FIG. 1e a flat roll-out view of a cardiac valve stent according to thefirst embodiment of the invention;

FIG. 2a a side view of a cardiac valve stent capable of supporting andanchoring an endoprosthesis according to a second embodiment of theinvention, where the cardiac valve stent is shown in its collapsedstate;

FIG. 2b a first perspective side view of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to the secondembodiment of the invention, whereby the cardiac valve stent is shown inits expanded state;

FIG. 2c a second perspective side view of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to the secondembodiment of the invention, where the cardiac valve stent is shown inits expanded state;

FIG. 2d a perspective side view of an endoprosthesis for treating anarrowed cardiac valve or a cardiac valve insufficiency, where theendoprosthesis comprises a cardiac valve stent according to the secondembodiment of the invention for holding an endoprosthesis;

FIG. 2e a flat roll-out view of a cardiac valve stent according to thesecond embodiment of the invention;

FIG. 3 a flat roll-out view of a cardiac valve stent according to thethird embodiment of the invention;

FIG. 4 a flat roll-out view of a cardiac valve stent according to thefourth embodiment of the invention;

FIG. 5a a first perspective side view of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to the fifthembodiment of the invention, whereby the cardiac valve stent is shown inits expanded state;

FIG. 5b a second perspective side view of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to the fifthembodiment of the invention, whereby the cardiac valve stent is shown inits expanded state;

FIG. 5c a plan view of the upper end of a cardiac valve stent capable ofsupporting and anchoring an endoprosthesis according to the fifthembodiment of the invention, whereby the cardiac valve stent is shown inits expanded state;

FIG. 5d a flat roll-out view of a cardiac valve stent according to thefifth embodiment of the invention;

FIG. 6a a first perspective side view of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to the sixthembodiment of the invention, whereby the cardiac valve stent is shown inits expanded state;

FIG. 6b a second perspective side view of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to the sixthembodiment of the invention, whereby the cardiac valve stent is shown inits expanded state;

FIG. 6c a third perspective side view of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to the sixthembodiment of the invention, whereby the cardiac valve stent is shown inits expanded state;

FIG. 6d a flat roll-out view of a cardiac valve stent according to thesixth embodiment of the invention;

FIG. 6e a perspective side view of an endoprosthesis for treating anarrowed cardiac valve or a cardiac valve insufficiency, where theendoprosthesis comprises a cardiac valve stent according to anembodiment of the invention for holding an endoprosthesis, whereby thecardiac valve stent is shown in a partly expanded state;

FIG. 6f a perspective side view of an endoprosthesis for treating anarrowed cardiac valve or a cardiac valve insufficiency, where theendoprosthesis comprises a cardiac valve stent according to the sixthembodiment of the invention for holding an endoprosthesis, whereby thecardiac valve stent is shown in an expanded state;

FIG. 6g a perspective detail view of the head portion of a retainingarch belonging to the cardiac valve stent of the endoprosthesis shown inFIG. 6 f;

FIG. 6h a perspective detail view of an additional fastening portionbelonging to the cardiac valve stent of the endoprosthesis shown in FIG.6 f;

FIG. 6i a plan view of the lower end of the endoprosthesis shown in FIG.6f , i.e. a view from the inflow side of the endoprosthesis shown inFIG. 6 f;

FIG. 7a a flat roll-out view of a cardiac valve stent according to theseventh embodiment of the invention;

FIG. 7b a first side view of a cardiac valve stent capable of supportingand anchoring an endoprosthesis according to the seventh embodiment ofthe invention, whereby the cardiac valve stent is shown in its expandedstate;

FIG. 7c a second perspective side view of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to the seventhembodiment of the invention, whereby the cardiac valve stent is shown inits expanded state;

FIG. 8a a flat roll-out view of a cardiac valve stent according to theeighth embodiment of the invention;

FIG. 8b a first perspective side view of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to the eighthembodiment of the invention, whereby the cardiac valve stent is shown inits expanded state;

FIG. 8c a second perspective side view of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to the eighthembodiment of the invention, whereby the cardiac valve stent is shown inits expanded state;

FIG. 9a a flat roll-out view of a cardiac valve stent according to theninth embodiment of the invention;

FIG. 9b a perspective side view of a cardiac valve stent capable ofsupporting and anchoring an endoprosthesis according to the ninthembodiment of the invention, whereby the cardiac valve stent is shown inits expanded state;

FIG. 10 a flat roll-out view of a cardiac valve stent according to thetenth embodiment of the invention;

FIG. 11 a flat roll-out view of a cardiac valve stent according to theeleventh embodiment of the invention;

FIG. 12 a flat roll-out view of a cardiac valve stent according to thetwelfth embodiment of the invention;

FIG. 13a a flat roll-out view of a cardiac valve stent according to thethirteenth embodiment of the invention;

FIG. 13b a first perspective side view of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to thethirteenth embodiment of the invention, whereby the cardiac valve stentis shown in its expanded state;

FIG. 13c a second perspective side view of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to thethirteenth embodiment of the invention, whereby the cardiac valve stentis shown in its expanded state;

FIG. 14a a flat roll-out view of a cardiac valve stent according to thefourteenth embodiment of the invention;

FIG. 14b a perspective side view of a cardiac valve stent capable ofsupporting and anchoring an endoprosthesis according to the fourteenthembodiment of the invention, whereby the cardiac valve stent is shown inits expanded state;

FIG. 15 a flat roll-out view of a cardiac valve stent according to thefifteenth embodiment of the invention;

FIG. 16a a flat roll-out view of a cardiac valve stent according to thesixteenth embodiment of the invention;

FIG. 16b a first perspective side view of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to the sixteenthembodiment of the invention, whereby the cardiac valve stent is shown inits expanded state;

FIG. 16c a second perspective side view of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to the sixteenthembodiment of the invention, whereby the cardiac valve stent is shown inits expanded state;

FIG. 16d a third perspective side view of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to the sixteenthembodiment of the invention, whereby the cardiac valve stent is shown inits expanded state;

FIG. 16e a plan view of the upper end of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to the sixteenthembodiment of the invention, whereby the cardiac valve stent is shown inits expanded state;

FIG. 16f a first perspective side view of an endoprosthesis for treatinga narrowed cardiac valve or a cardiac valve insufficiency, where theendoprosthesis comprises a cardiac valve stent according to thesixteenth embodiment of the invention for holding an endoprosthesis,whereby the cardiac valve stent is shown in an expanded state;

FIG. 16g a second perspective side view of an endoprosthesis fortreating a narrowed cardiac valve or a cardiac valve insufficiency,where the endoprosthesis comprises a cardiac valve stent according tothe sixteenth embodiment of the invention for holding an endoprosthesis,whereby the cardiac valve stent is shown in an expanded state;

FIG. 17a a flat roll-out view of a cardiac valve stent according to theseventeenth embodiment of the invention;

FIG. 17b a first perspective side view of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to theseventeenth embodiment of the invention, whereby the cardiac valve stentis shown in its expanded state;

FIG. 17c a second perspective side view of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to theseventeenth embodiment of the invention, whereby the cardiac valve stentis shown in its expanded state;

FIG. 17d a third perspective side view of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to theseventeenth embodiment of the invention, whereby the cardiac valve stentis shown in its expanded state;

FIG. 17e a plan view of the upper end of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to theseventeenth embodiment of the invention, whereby the cardiac valve stentis shown in its expanded state;

FIG. 18a-c a process sequence illustrating a transarterial implantationof an aortic endoprosthesis comprising a cardiac valve stent inaccordance with certain embodiments of the invention and a valvularprosthesis affixed to the stent;

FIG. 19a a first perspective side view of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to theeighteenth embodiment of the invention, whereby the cardiac valve stentis shown in its expanded state;

FIG. 19b a second perspective side view of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to theeighteenth embodiment of the invention, whereby the cardiac valve stentis shown in its expanded state;

FIG. 20a a flat roll-out view of a cardiac valve stent according to thenineteenth embodiment of the invention, whereby the cardiac valve stentis in its non-expanded state;

FIG. 20b a first perspective side view of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to thenineteenth embodiment of the invention, whereby the cardiac valve stentis shown in its expanded state;

FIG. 20c a second perspective side view of a cardiac valve stent capableof supporting and anchoring an endoprosthesis according to thenineteenth embodiment of the invention, whereby the cardiac valve stentis shown in its expanded state;

FIG. 20d a flat roll-out view of a cardiac valve stent according to thenineteenth embodiment of the invention, whereby the cardiac valve stentis in its expanded state;

FIG. 21 a flat roll-out view of a cardiac valve stent according to thetwentieth embodiment of the invention, whereby the cardiac valve stentis shown in its expanded state; and

FIG. 22 a flat roll-out view of a cardiac valve stent according to thetwenty-first embodiment of the invention, whereby the cardiac valvestent is shown in its expanded state.

Both the right and left halves of the human heart consist of a ventricleand an atrium. These cavities are separated by the septum of the heart,divided into the atrial septum (septum interatriale) and the ventricularseptum (septum interventriculare).

Blood can only flow in one direction through the chambers of the heartdue to the cardiac valves situated between the atria and ventricles andin the arteries connected to the ventricles which function likemechanical valves. The superior and inferior vena cava (vena cavasuperior et inferior) flow into the right atrium. They supply theoxygen-depleted (venous) blood from the systemic circulation to theheart. The tricuspid valve which, like a mechanical valve, prevents areverse flow of blood into the atrium upon ventricular contraction(systole) is situated between the right atrium and the right ventricle.It comprises three segments, also called leaflets, which are affixedlike flaps to the ventricular musculature by ligaments (hence alsocalled the “flap valve”). The two pulmonary arteries depart the rightventricle of the heart via a common trunk (truncus pulmonalis). There isalso a valve between the ventricle and the pulmonary trunk, theso-called, pulmonary valve. This type of valve is also called asemilunar valve due to its shape. The pulmonary arteries supply theoxygen-depleted blood to the pulmonary circulation.

Oxygen-rich (arterial) blood then usually flows through four pulmonaryveins from the pulmonary circulation to the left atrium. From there, itreaches the left ventricle through a further flap valve, the mitralvalve. The outflow is carried by the aorta which, like the pulmonaryartery, has a semilunar valve (aortic valve).

During a heart cycle, the atria fill first while the ventriclesconcurrently disgorge the blood into the arteries. When the ventricularmusculature relaxes, the flap valve open due to the drop in pressure inthe ventricle and the blood flows in from the atria (auricular systole).This is supported by a contraction of the atria. Ventricular contractionfollows: the ventricular musculature contracts, the pressure rises, theflap valves close and the blood can now only flow into the arteriesthrough the now-opened semilunar valves. A reverse blood flow from thearteries during the relaxation phase (diastole) is prevented by theclosing of the semilunar valves such that the direction of flow isdetermined solely by the valves.

The four cardiac valves work like mechanical valves in the heart andprevent a reverse flow of blood in the wrong direction. Each half of theheart has a flap valve (atrioventricular valve) and a semilunar valve.The atrioventricular valves are situated between the atrium and theventricle and are called the bicuspid/mitral valve and the tricuspidvalve. The semilunar valves are situated between the ventricle and thevascular outflow and are called the pulmonary valve and the aortic valverespectively.

A valve defect; i.e. a dysfunction of a cardiac valve's function, canaffect any of the four cardiac valves, although the valves on the leftside of the heart (aortic and mitral valves) are affected considerablymore frequently than those on the right side of the heart (pulmonary andtricuspid valves). Dysfunction can encompass constriction (stenosis),insufficiency or a combination of the two (combined vitium).

In medicine, the term “aortic valve insufficiency”, or “aorticinsufficiency” for short, refers to the defective closing of the heart'saortic valve and the diastolic reverse flow of blood from the aorta intothe left ventricle as a result. Depending on the severity of the aorticinsufficiency and the extent of resistance to aortic depletion, thevolume of reverse flow can be up to two thirds of the left ventricle'sejection volume (normal cardiac output 40 to 70 ml). This results incharacteristically high blood pressure amplitude. This regurgitate bloodflow increases the diastolic filling of the left chamber and leads to avolume overload of this section of the heart, a consequence of which iseccentric hypertrophy.

Aortic valve stenosis is a valvular heart disease caused by theincomplete opening of the aortic valve. When the aortic valve becomesstenotic, it causes a pressure gradient between the left ventricle andthe aorta. The more constricted the valve, the higher the gradientbetween the left ventricle and the aorta. For instance, with a mildaortic valve stenosis, the gradient may be 20 mmHg. This means that, atpeak systole, while the left ventricle may generate a pressure of 140mmHg, the pressure that is transmitted to the aorta will only be 120 mmHg.

In individuals with aortic valve stenosis, the left ventricle has togenerate an increased pressure in order to overcome the increased afterload caused by the stenotic aortic valve and eject blood out of the leftventricle. The more severe the aortic stenosis, the higher the gradientis between the left ventricular systolic pressures and the aorticsystolic pressures. Due to the increased pressures generated by the leftventricle, the myocardium (muscle) of the left ventricle undergoeshypertrophy (increase in muscle mass).

Angina in the setting of aortic valve stenosis is secondary to the leftventricular hypertrophy that is caused by the constant production ofincreased pressure required to overcome the pressure gradient caused bythe aortic valve stenosis. While the myocardium (i.e. heart muscle) ofthe left ventricle gets thicker, the arteries that supply the muscle donot get significantly longer or bigger, so the muscle may becomeischemic (i.e. doesn't receive an adequate blood supply). The ischemiamay first be evident during exercise, when the heart muscle requiresincreased blood supply to compensate for the increased workload. Theindividual may complain of exertional angina. At this stage, a stresstest with imaging may be suggestive of ischemia.

Mitral valve insufficiency (also called mitral insufficiency) is afrequent cardiac valve defect in human medicine and also in at leastsome animal species. It involves a closing defect or “leakage” of theheart's mitral valve which leads to reverse blood flow from the leftventricle into the left atrium during the ejection phase (systole).

The mitral valve functions like a mechanical valve between the leftatrium and the left ventricle of the heart. It opens during the fillingphase of the ventricle (diastole) and thus enables the inflow of bloodfrom the atrium. At the beginning of the ejection phase (systole), thesudden increase in pressure in the ventricle leads to the closing of thevalve and thus to a “sealing” of the atrium. In so doing, a pressure ofonly about 8 mmHg prevails in the atrium, while at the same time thesystolic pressure of about 120 mmHg in the ventricle forces the bloodalong its usual path into the main artery (aorta).

In cases of severe mitral insufficiency, however, the regurgitationopening is larger than 40 mm² and the regurgitation volume greater than60 ml, which can lead to serious and at times life-threatening changes.

In the acute stage, with a normal size to the left ventricle and theleft atrium, there is a considerable increase of the pressure in theatrium and thus also in the pulmonary veins. This can be up to 100 mmHgwhich, given a normal condition to the pulmonary vessels, leads toimmediate pulmonary oedema. The then predominantly reverse blood flowcan result in insufficient outflow into the aorta and thus decreasedblood flow to all the organs.

To treat a severe narrowed cardiac valve or cardiac valve insufficiency,it is necessary for an endoprosthesis to perform the valve function ofthe narrowed or diseased cardiac valve. Essential in this respect isthat the endoprosthesis is securely positioned and anchored in theimplantation site in the heart; i.e. in the plane of the (diseased)cardiac valve to be replaced, so that the endoprosthesis is notdisplaced or shifted despite the, at times considerable, forces actingon it. Also, an effective seal during systole is important for themitral valve and during diastole for the aortic valve.

The present invention relates to an expandable stent for anendoprosthesis used in the treatment of a stenosis (narrowing) of acardiac valve and/or a cardiac valve insufficiency. Furthermore, thepresent invention relates to a collapsible and expandable prosthesisincorporating a stent that can be delivered to the implant site using acatheter for treatment of a stenosis (narrowing) of a cardiac valveand/or a cardiac valve insufficiency. Although the inventive stent andthe valvular prosthesis affixed thereto can be used for replacing any ofthe four different heart valves, in particular the pulmonary valve andthe aortic valve, the application of the invention for treatment of adiseased aortic valve is described in the following only for reasons ofsimplification.

A cardiac valve stent 10, to which the valvular prosthesis 100 isappropriately affixed, is employed in accordance with at least certainembodiments of the invention to position and anchor said endoprosthesis.A medical device for the treating of a narrowed cardiac valve or acardiac valve insufficiency consisting of a cardiac valve stent 10 and avalvular prosthesis 100 affixed to the stent 10 will be referred toherein simply as endoprosthesis 1.

FIG. 1d shows a side view of such an endoprosthesis 1 for treating anarrowed cardiac valve or a cardiac valve insufficiency, whereby theendoprosthesis 1 comprises a cardiac valve stent 10 to hold a valvularprosthesis 100 in accordance with a first embodiment of the invention.FIG. 2d likewise shows a side view of a further endoprosthesis 1 fortreating a narrowed cardiac valve or a cardiac valve insufficiency,whereby a cardiac valve stent 10 in accordance with a second embodimentof the invention is employed.

The following description will make reference to the drawings todescribe preferred embodiments of the present invention in detail. Thecardiac valve stent 10 according to certain embodiments of the invention(hereinafter referred to simply as “stent”) exhibits an expandablestructure which is able to transform from a first predefinable shape inwhich the stent 10 is in a collapsed state into a second predefinableshape in which the stent 10 is in an expanded state. FIG. 1a shows aside view of a stent 10 according to the first embodiment of theinvention, whereby the stent 10 is in its collapsed state. FIG. 2a showsthe collapsed stent. 10 according to a second embodiment of theinvention.

In the two embodiments, the stent 10 together with a valvular prosthesisaffixed thereon is introduced in a minimally-invasive fashion into thebody of a patient in its first shape (cf. FIG. 1a and FIG. 2a ) using aninsertion catheter system (not explicitly shown in the drawings). Duringinsertion, a valvular prosthesis 100 affixed to the stent 10 is likewisein a collapsed state. For the sake of clarity, however, both FIGS. 1aand 2a dispense with a representation of the valvular prosthesis 100affixed to the stent 10.

Upon reaching the site of implantation in the patient's heart, the stent10 transforms, through increments, into its expanded shape in which alsothe valvular prosthesis 100 affixed to the stent 10 also unfolds andexpands. The expanded shape of the stent 10 is a permanent shape thathas been set by programming. The completely expanded stent 10 accordingto the first/second embodiment of the invention with the likewisecompletely unfolded and expanded valvular prosthesis 100 affixed theretois shown in FIG. 1d and FIG. 2d . It is important to note that thesecond shape of the stent 10, i.e. the shape of the stent 10 in itsfully expanded but not-implanted state, may differ from the shape of thestent 10 in its fully expanded and implanted state, because, in theimplanted state, the shape of the fully expanded stent 10 is at leastpartly limited by the anatomy at the implantation site.

FIG. 1b and FIG. 1c show the completely expanded stent 10 according tothe first embodiment of the invention from different perspectiveswithout the valvular prosthesis 100. FIGS. 2b and 2c show the completelyexpanded stent 10 according to the second embodiment of the invention,likewise without the valvular prosthesis 100, from differentperspectives.

The following will initially make reference to FIGS. 1a to 1e indescribing the first embodiment of the stent 10.

The stent 10 according to the first embodiment exhibits a structureintegrally cut from a portion of tube, in particular a metal tube. Thecutting pattern used to form the design of the stent is depicted in atwo-dimensional projection in FIG. 1 e.

In detail, the stent 10 has three positioning arches 15 a, 15 b, 15 cwhich assume the function of self-positioning the stent into the planeof the pulmonary valve. (valva trunci pulmonalis) or aortic valve (valvaaortae). The positioning arches 15 a, 15 b, 15 c exhibit a rounded headportion 20 which engages in the pockets T of the (diseased) cardiacvalve to be treated during positioning of the stent 10 at the site ofimplantation in the heart (cf. FIG. 18a ).

As well as providing a symmetry that matches that of the native valve,the provision of three positioning arches 15 a, 15 b, 15 c also providesrotational accuracy, symmetry and stability. The stent 10 is of coursenot limited to the use of a total of three positioning arches.

The head portions 20 of the positioning arches 15 a, 15 b, 15 c,respectively pointing towards the lower end 2 of the stent 10, arerounded so that the vascular wall will not be damaged when thepositioning arches 15 a, 15 b, 15 c engage in the pockets T of thecardiac valve H to be replaced. To improve movement and positionanalysis during the implanting of the stent 10 reference markers 21 areprovided on or within the head portions 20 of the positioning arches 15a, 15 b, 15 c. Radio opaque markers or markers which can be activated byinfrared or ultrasound lend themselves particularly well hereto.

The positioning arches 15 a, 15 b, 15 c respectively exhibit anessentially U-shaped or V-shaped structure which is closed to the lowerend of stent 10. Accordingly, each positioning arch 15 a, 15 b, 15 c hasa total of two arms 15 a′, 15 a″, 15 b′, 15 b″, 15 c′, 15 c″respectively extending from the head portion 20 of the associatedpositioning arch 15 a, 15 b, 15 c towards the upper end 3 of stent 10.By doing so, each two adjoining arms of two neighbouring positioningarches are connected to one another via a connecting portion 22.

For implanting and explanting the stent 10 together with a valvularprosthesis affixed thereto with a suitable catheter system, the stent 10comprises catheter retaining means 23 at its upper end 3. The connectingportions 22 are respectively connected to catheter retaining means. 23via a connecting web 25. The connecting webs 25 will hereinafter bereferred to as “second connecting web 25”.

The catheter retaining means 23 comprise oval-shaped heads which eachcomprise a corresponding oval-shaped eyelet 24. The shape of thecatheter retaining means 23 complements a crown on the tip of a catheterof a catheter system used to implant/explant stent 10. The crown on thecatheter tip has protruding elements that are configured as a negativeof the catheter retaining means 23. Alternatively, the protrudingelements are shaped to be complementary to the eyelets 24 and areconfigured as catheter retaining heads. This realization enables theprotruding elements of the crown to form a releasable engagement withthe upper area 3 of stent 10 to allow releasable attachment of the stent10 to the tip of the catheter.

A first connecting web 17 extends essentially in the longitudinaldirection L of stent 10 and has an upper end portion 17 d and a lowerend portion 17 p. The upper end portion 17 d opens into connectingportion 22 between the two arms 15 a′, 15 a″, 15 b′, 15 b″, 15 c′, 15 c″of two neighboring positioning arches 15 a, 15 b, 15 c, in addition tothe previously-mentioned second connecting web 25. As can be seen inFIG. 1b , the first connecting webs 17 have an essentially invertedY-shaped configuration and each exhibit a structure that diverges at itslower end portion 17 p to give way to the respective arms 16 a′, 16 a″,16 b′, 16 b″, 16 c′, 16 c″ of two neighboring retaining arches 16 a, 16b, 16 c.

In between each positioning arch 15 and retaining arch 16 is a fasteningarch 19. As is shown particularly clearly in FIG. 1b , the fasteningarch extends from the lower end of fastening portion 11 and has asubstantially U-shaped or V-shaped structure which is closed to thelower end of stent 10. As is shown in FIG. 1d , the fastening archesserve to support the lower end of valve prosthesis 100. The prosthesis100 is shaped so that fastening arches 19 a, 19 b and 19 c are locatedin pockets of the valve material.

This stent design achieves an axially symmetrical structure, wherebyeach positioning arch 15 a, 15 b, 15 c is allocated one fastening arch19 a, 19 b, 19 c and one retaining arch 16 a, 16 b, 16 c. The stent 10of the first embodiment depicted in FIGS. 1a to 1d thus comprises atotal of three retaining arches 16 a, 16 b, 16 c which constitutes aretaining segment of stent 10 for accommodating a valvular prosthesis100 as depicted for example in FIG. 1 d.

In the state of the stent 10 shown in FIG. 1a , in which stent 10 is inits first (collapsed) shape, the respective arms 15 a′, 15 a″, 15 b′, 15b″, 15 c′, 15 c″ of the positioning arches 15 a, 15 b, 15 c directlyadjoin the respective arms 19 a′, 19 a″, 19 b′, 19 b″, 19 c′, 10 c″ ofthe fastening arches 19 a, 19 b, 19 c which, in turn, directly adjointhe respective arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of theassociated retaining arches 16 a, 16 b, 16 c.

Reference is made to FIG. 1b , in which the stent 10 pursuant to thefirst embodiment is shown in its second, expanded shape. It can beparticularly recognized from this representation that each positioningarch 15 a, 15 b, 15 c and associated fastening arch 19 a, 19 b, 19 c andretaining arch 16 a, 16 b, 16 c respectively exhibit an essentiallyU-shaped or V-shaped structure which is closed towards the lower end 2of the stent 10. Specifically, each positioning arch 15 a, 15 b, 15 c iscut from a material section of a portion of a tube from which theessentially U-shaped or V-shaped structure of the associated fasteningarch 19 a, 19 b, 19 c was taken, as can be seen from the cutting patterndepicted in FIG. 1 e.

A comparison of FIG. 1a to FIG. 1b shows that, upon the stent 10expanding; i.e. when the stent 10 transforms from its first shape intoits second shape, the stent 10 shortens in the longitudinal direction Lwhile simultaneously enlarging in cross-section. In the expanded stateof stent 10, the positioning arches 15 a, 15 b, 15 c are expanded morein the radial direction at the lower end 2 of the stent 10 compared tothe upper end 3 of stent 10. Since they protrude more in the radialdirection, the positioning arches 15 a, 15 b, 15 c can be deployed intothe cardiac valve pockets T of the cardiac valve H to be replaced in aparticularly easy manner.

Even when a certain anchoring of the stent 10 together with a valvularprosthesis affixed thereto is achieved at the site of implantation inthe heart due to the positioning arches 15 a, 15 b, 15 c alreadyprotruding radially from stent 10 in the expanded state of the stent 10,it is noted that the contact force acting on the vascular wall from thepositioning arches 15 a, 15 b, 15 c is insufficient to securely anchorthe stent 10 at the site of implantation. The previously-mentionedretaining arches 16 a, 16 b, 16 c, which form the lower end 2 of stent10, are provided for this reason. The retaining arches 16 a, 16 b, 16 cprotrude radially from the circumference of the stent 10 in its expandedstate such that the retaining arches 16 a, 16 b, 16 c press against thewall of the blood vessel in which the stent is deployed with aradially-acting contact force. In addition, the closed ends of theretaining arches 16 a, 16 b, 16 c flare outwards, protruding radiallystill further from the circumference of the stent 10. This shape allowsthe ends of the retaining arches 16 a, 16 b, 16 c to be positioned belowthe native valve annulus or to be positioned at least on the nativevalve annulus, thereby providing additional anchoring for the stent 10together with a valvular prosthesis affixed thereto.

In addition to retaining arches 16 a, 16 b, 16 c, the stent 10 furthercomprises auxiliary arches 18 a, 18 b, 18 c, which likewise exert aradially-acting contact force against the wall of the blood vessel inthe implanted state of stent 10, thereby further improving anchoring ofstent 10 and a valvular prosthesis affixed thereto at the site ofimplantation.

As can be seen from FIG. 1b , stent 10 comprises a total of threeessentially U-shaped or V-shaped auxiliary arches 18 a, 18 b, 18 c whichare closed towards the lower end 2 of said stent 10. Each auxiliary arch18 a, 18 b, 18 c connects a first retaining arch 16 a, 16 b, 16 c with asecond retaining arch neighboring the first retaining arch.

In a top plan view of the lower end region 2 of the expanded stent 10(cf. FIG. 1c ), the lower end region 2 exhibits a dodecagonal polygonalstructure formed from the individual arms 16 a′, 16 a″, 16 b′, 16 b″, 16c′, 16 c″ of retaining arches 16 a, 16 b, 16 c and the individual arms18 a′, 18 a″, 18 b′, 18 b″, 18 c′, 18 c″ of the auxiliary arches 18 a,18 b, 18 c. This stent design particularly provides a total of sixarches 16 a, 16 b, 16 c, 18 a, 18 b, 18 c uniformly distributed aroundthe lower end region 2 of stent 10, each of which press against thevascular wall and effectively hold the stent 10 in position in theexpanded and implanted state of stent 10 together with a valvularprosthesis affixed thereto.

To recapitulate, providing retaining arches 16 a, 16 b, 16 c on the onehand and auxiliary arches 18 a, 18 b, 18 c on the other results in aradial force being exerted on the vascular wall by the respective lowerend portions of these arches. This ensures both a secure seal of avalvular prosthesis 100 affixed to stent 10 relative the vascular wall,as well as a secure anchoring of the stent 10, at the site ofimplantation in the heart.

In addition to the contact force exerted on the vascular wall by way ofthe retaining arches 16 a, 16 b, 16 c and auxiliary arches 18 a, 18 b,18 c, it is conceivable for the upper end region 3 of stent 10 to expandradially 10% to 25% more—in the fully expanded but not implanted stateof stent 10—compared to the lower end region 2. This gives the stent 10a slight concave structure which tapers towards the lower end region 2.However, in its fully expanded and implanted state, the upper endsection 3 of the stent 10 may not be expanded radially 10% to 25% morecompared to the lower end region 2 because the shape of the stent in itsimplanted state is limited by the anatomy in the implantation side.However, the upper end section 3 of the stent 10 tends to spreadradially somewhat relative to the annular diameter of the constrainedlower end section 2 of the stent 10. This ensures secure anchoring ofthe stent 10 within the vessel by the upper end region 2 of the stent 10pressing against the vascular wall.

To ensure that minimal longitudinal displacement of a valvularprosthesis affixed to stent 10 can occur relative stent 10, even duringthe peristaltic movement of the heart and the blood vessel in whichstent 10 together with a valvular prosthesis affixed thereto isdeployed, the embodiment of the inventive stent 10 depicted in thedrawings provides for the stent 10 to comprise a plurality of fasteningportions 11 extending in the longitudinal direction L of stent 10, bymeans of which the tissue component(s) of a valvular prosthesis 100 isaffixed to the stent 10. Reference is made to FIG. 1d which shows a sideview of an endoprosthesis 1 for treating a narrowed cardiac valve or acardiac valve insufficiency. The endoprosthesis 1 comprises the stent 10pursuant the first embodiment of the invention holding a valvularprosthesis 100. The valvular prosthesis 100 comprises at least oneleaflet 102 made from a biological or synthetic material.

It will be appreciated that the valvular prosthesis may be made from anysuitable material, including biological valves removed from animals suchas pigs and horses, man-made biological valves created from connectivetissue such as pericardium, tissue grown from cell cultures, andman-made materials and fabrics such as nitinol.

In detail, the first connecting webs 17 of stent 10 connect withconnecting portions 22 via their upper ends 17 d and with the upper ends13 of fastening portions 11 via their lower ends 17 p. The respectivelower ends 14 of the fastening portions which are connected to one andthe same connecting web 17 are thereby connected together via anessentially U-shaped or V-shaped auxiliary arch 18 a, 18 b, 18 c whichis closed towards the lower end 2 of stent 10.

Specifically, the first embodiment of the inventive stent 10 is shown inFIG. 1d in its expanded state, whereby a valvular prosthesis 100 isfastened to said stent 10 by means of a thread 101 or a thin wire andstretched by the stent 10. It is easily recognized that the widening ofthe centre area and the lower end region 2 of stent 10 at which thevalvular prosthesis 100 is disposed achieves spreading of theendoprosthesis. At the same time, the lower end portions of theretaining arches 16 a, 16 b, 16 c and the auxiliary arches 18 a, 18 b,18 c exert a radial force on the (not shown in FIG. 1d ) vascular wall.

As can be seen from FIG. 1d , a defined plurality of fastening holes 12are configured in the respective fastening portions 11 of stent 10, andare arranged to be distributed at predefined longitudinal positionsalong the fastening portions 11. The thread 101 or thin wire with whichthe tissue component(s) of the valvular prosthesis 100 is attached tostent 10 is guided through each respective fastening hole 12.

Both components constituting the endoprosthesis 1, namely the stent 10and the valvular prosthesis 100, may be connected together prior to thesurgical procedure. The so constructed endoprosthesis 1 can be stored inits expanded shape for a long period of time without structuraldeterioration in the tissue of the valvular prosthesis 100. Theendoprosthesis 1 shall be compressed and brought into its collapsedshape directly prior to the surgical procedure. Then, the endoprosthesis1 is ready for being inserted into a catheter system which is used forimplanting the endoprosthesis 1.

It is conceivable of course that both components constituting theendoprosthesis 1, namely the stent 10 and the valvular prosthesis 100,are not connected together until directly prior to the surgicalprocedure. Then, the stent 10 shall be stored in its second shape; i.e.in the expanded state, and not brought into its first (collapsed) shapeuntil directly prior the surgical procedure.

It can be noted from FIGS. 1b and 1d that the respective fasteningportions 11 are configured in the respective arms 16 a′, 16 a″, 16 b′,16 b″, 16 c′, 16 c″ of retaining arches 16 a, 16 b, 16 c of stent 10.The size of the fastening holes 12 configured in the fastening portions11 should be adapted to the thickness of the thread 101 or wire used tofasten the tissue component(s) of the valvular prosthesis 100 to thestent 10.

The cross-sectional shape to the fastening holes 12 may also be adaptedto the cross-sectional shape of the thread 101 or wire used to fastenthe valvular prosthesis 100. This allows fixing of the valvularprosthesis 100 to the stent 10 at a precise predefined position relativeto the stent 10. By providing of a plurality of fastening holes 12 toanchor the valvular prosthesis 100 to the stent 10, precise positioningof the valvular prosthesis on stent 10 is achieved.

Because the fastening holes 12 are adapted to the thickness and/or thecross-sectional shape of the thread 101 or wire used to affix thevalvular prosthesis 100 to the stent 10, relative movement between thestent 10 and the valvular prosthesis 100 due to the peristaltic motionof the heart can be effectively prevented when the endoprosthesis 1 isimplanted. In the fully expanded and implanted state of theendoprosthesis 1, the valvular prosthesis 100 is thus fastened to thestent 10 with minimal play, based on which friction-induced wear of thethread 101 or wire used to affix the valvular prosthesis is minimized.As shown in the figures the fastening holes 12 have a circularcross-sectional shape.

Although the valve tissue, i.e. the tissue component(s) of the valvularprosthesis 100, shall be securely fastened to the stent 10, it isnecessary that the valve tissue must be capable of deforming withoutdamage to allow for the stent lengthening when collapsed.

As already mentioned, the fastening holes 12 configured in therespective fastening portions 11 may be of different diameters, numbersor cross-sectional shapes (oval, square, etc) according to the diameterof a thread 101 used for affixing the tissue component(s) of thevalvular prosthesis 100 to the stent 10, and/or according to the sewingtechnique utilized for affixing the valvular prosthesis 100 to the stent10. The diameter, number and/or cross-sectional shape of at least one ofthe fastening holes 12 may also serve as an indication of the type ofthe endoprosthesis 1, i.e. the medical device used in the treatment of anarrowing of a cardiac valve and/or a cardiac valve insufficiency. Inthis respect, the diameter, number and/or cross-sectional shape of theat least one fastening hole 12 may be used for identification todifferentiate between different sizes or types of valvular prostheses100 adapted to be fixed on the stent 10, or may be used foridentification to differentiate between different sizes or types ofendoprostheses 1, if a valvular prosthesis 100 is already fixed to thestent 10. For example, a small-sized stent 10 having a small-sizedvalvular prosthesis 100 fixed thereto or a small-sized stent 10 adaptedand configured for carrying a small-sized valvular prosthesis 100 couldhave circular fastening holes 12 whilst a large-sized stent 10 having alarge-sized valvular prosthesis 100 fixed thereto or a large-sized stent10 adapted and configured for carrying a large-sized valvular prosthesis100 may have triangular fastening holes 12. This allows thesurgeon/cardio staff to easily and visually tell different valve sizes,stent types and/or types of the valvular prosthesis apart without theneed to measure.

In the first embodiment depicted in FIGS. 1a-e , the fastening portions11 of the stent 10 (onto which the valvular prosthesis 100 is sewn orsewable) do not change their shape when the stent 10 is compressed, e.g.when the stent 10 is in its first (collapsed) shape shown in FIG. 1a .This phenomenon occurs when standard tube stents are used. Thus the riskof thread wear is minimal.

As described in detail with respect to the sixteenth and seventeenthembodiments of the present invention, however, the retaining archestogether with the fastening portions provided in the respective arms ofthe retaining arches may also be configured such that they do changetheir shape when the stent 10 is compressed. In detail, according to thesixteenth and seventeenth embodiments of the inventive stent design, theretaining arches are curved in the expanded state of the stent, butrelatively straight when the stent is collapsed.

A stent 10 in accordance with a second embodiment is depicted in FIGS.2a to 2c and is similar in structure and function to the firstembodiment of the stent 10 depicted in FIGS. 1a to 1c . The same alsoholds true for the cutting pattern depicted in FIG. 2e which is, inprinciple, comparable to the cutting pattern according to FIG. 1e . Adetailed description of the common features will therefore not beprovided.

A difference to be seen is in the configuration of the catheterretaining means 23 provided at the upper end section 3 of stent 10. Incontrast to the first embodiment of the inventive stent 10, heads of anessentially round configuration are used as catheter retaining means 23in the second embodiment, in each case provided with essentially ovaleyelets 24. Due to the round configuration of the heads the risk ofproducing injury or damage is lowered. Hence, an essentially roundconfiguration of the heads is more atraumatic.

As already indicated, the stent 10 according to certain embodiments ofthe present invention preferably exhibits a structure integrally cutfrom a portion of tube, and in particular from a metal tube. A fasteningarch 19 a, 19 b, 19 c and a retaining arch 16 a, 16 b, 16 c is allocatedto each positioning arch 15 a, 15 b, 15 c, and each retaining arch 16 a,16 b, 16 c is connected to a neighboring retaining arch by means of anauxiliary arch 18 a, 18 b, 18 c. A fastening portion 11 with a specificnumber of fastening holes 12 is configured in each arm 16 a′, 16 a″, 16b′, 16 b″, 16 c′, 16 c″ of retaining arch 16 a, 16 b, 16 c.

FIGS. 1e and 2e each show a flat roll-out view of a stent 10 pursuantthe first or second embodiment of the invention. These flat roll-outviews respectively correspond to two-dimensional projections of acutting pattern which can be used in the manufacture of the stent 10pursuant the first or second embodiment of the invention. This enables aone-piece stent 10 to be cut from a portion of tube, in particular ametal tube. It is evident that, on the one hand, the inventive stent 10dispenses with fixed-body joints or other similar connective devicesbetween the individual components of stent 10 (positioning arch,retaining arch, auxiliary arch). On the other hand, a stent 10 isprovided which exhibits, with minimum longitudinal extension, thefunctionality of positionability as provided by the positioning arches15 a, 15 b, 15 c on the one hand and, on the other, the functionality ofthe defined fastening of a valvular prosthesis 100, as provided by thefastening portions 11 configured in the respective arms 16 e, 16 a″, 16b′, 16 b″, 16 c′, 16 c″ of the retaining arch 16 a, 16 b, 16 c.

In addition to its retaining arches 16 a, 16 b, 16 c, the stent 10further comprises auxiliary arches 18 a, 18 b, 18 c which enable aparticularly secure anchoring of stent 10 in the site of implantation inthe heart.

A stent 10 according to a third embodiment of the invention also has aone-piece structure cut from a portion of a tube, in particular from ametal tube. The cutting pattern used to form the stent design is shownin a two-dimensional projection in FIG. 3.

The differences between the third embodiment of the stent and the firstor second embodiments can be seen by referring to the two-dimensionalcutting pattern shown in FIG. 3. As is also the case in the first orsecond embodiment, the third embodiment of the stent 10 has a total ofthree positioning arches 15 a, 15 b, 15 c, which undertake the functionof automatic positioning of the cardiac valve stent in the plane of thepulmonary valve or the aortic valve.

The stent 10 is made from Nitinol and positioning arches 15 a, 15 b, 15c are programmed during manufacture, by a suitable heat treatment of thepositioning arches 15 a, 15 b, 15 c, so that, in the stent's expandedstate, i.e. when the permanent shape has been assumed after exceedingthe switching temperature, the positioning arches not only spread apartin a radial direction, as illustrated in FIGS. 1b, 1d and 2b, 2d , butsimultaneously curve in a slightly convex manner in the direction of thestent 10. This measure makes it possible for the head portions 20 of thepositioning arches 15 a, 15 b, 15 c to lie parallel with thelongitudinal axis L of the expanded stent 10 in an ideal manner. As aresult, during the implantation of the cardiac valve stent 10, the headportions 20 of the positioning arches 15 a, 15 b, 15 c can be insertedparticularly easily into the pockets T of the native heart valve H (seeFIG. 18a ). In particular, this minimizes damage to surrounding tissuewhen the positioning arches 15 a, 15 b, 15 c are inserted into thepockets T of the native heart valve H. The shape also allows thepositioning arches 15 a, 15 b, 15 c to exert an additional clippingforce on the native valve leaflets by pinching the native leaflet at thebottom of each arch.

In addition, the convex curvature of the positioning arches 15 a, 15 b,15 c enables an especially secure support of the stent 10 at theimplantation site since the positioning arches 15 a, 15 b, 15 c arebetter adapted to the anatomy of the pockets T of the native heartvalves H and their surroundings.

As in a stent 10 according to the first and second embodiment (see forexample FIGS. 1b, 1c, 1d and 2b, 2c, 2d ), a stent 10 of the thirdembodiment, has catheter retaining means 23 with eyelets 24. As withpreviously described embodiments, a suitable catheter system can bereleasably coupled to the catheter retaining means 23 to facilitate aminimally-invasive, transvascular implantation and explantation of thestent 10.

As with the stent 10 of the first or second embodiment, the retainingarches 16 a, 16 b, 16 c and auxiliary arches 18 a, 18 b, 18 c serve tosecure radial fixing of the stent 10 at the implantation site and forstretching a valvular prosthesis fastened to the stent by way offastening arches 19 a, 19 b, 19 c. No further discussion is needed toexplain that the retaining arches 16 a, 16 b, 16 c and the auxiliaryarches 18 a, 18 b, 18 c of this embodiment of the stent also function toseal an implanted valvular prosthesis. Similarly, the retaining arches16 a, 16 b, 16 c and positioning arches 15 a, 15 b, 15 c clamp thenative heart valve H like a paperclip and consequently contribute to thesecure anchoring of the stent 10 at the implantation site in the heart.

Stent 10 according to the third embodiment differs from the first andsecond embodiments in that the respective arms 16 a′, 16 a″, 16 b′, 16b″, 16 c′, 16 c″ of each retaining arch 16 a, 16 b, 16 c extend from thefastening portion 11 to the lower end 2 of the cardiac valve stent andare connected together by means of a connecting portion 30. Theconnecting portion 30 has a different shape when compared with theU-shaped or V-shaped connecting portions 30 in the embodiments accordingto FIGS. 1b, 1c, 1d and 2b, 2c, 2d . In particular, the connectingportion 20 has a waist just above the corresponding connecting portion30′ of the fastening arch. The waists in the retaining and fasteningarches accommodate an enlarged head 31 at the lower end of eachauxiliary arch 18 a, 18 b, 18 c.

Looking at FIG. 3 in detail, each connecting portion 30 which connectsthe two arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of a retainingarch 16 a, 16 b, 16 c has almost an O-shaped configuration. This shapeoffers more space for fastening a valvular prosthesis 100 to the stent10 and also effectively counteracts the occurrence of load peaks whichcan occur in the implanted state of the endoprosthesis during thetransmission of loads between the valvular prosthesis and the stent.

The alternative shape of the connecting portion 30 further increases theeffective contact area between the lower end of the retaining arch 16 a,16 b, 16 c and the vessel wall, when the stent is positioned at theimplantation site in its expanded state. Because of this, an improvedseal can be obtained between the stent with the valvular prosthesisattached to it and the vessel wall. Furthermore, the radial forcesacting in the expanded state of the stent, which are transmitted via theretaining arches 16 a, 16 b, 16 c to the vessel wall, are distributedover a discrete contact area, thereby counteracting the occurrence ofload peaks. The risk of damage from the retaining arches 16 a, 16 b, 16c to the vessel wall is also reduced.

Each connecting portion 30′ which connects the two arms 19 a′, 19 a″, 19b′, 19 b″, 19 c′, 19 c″ of a fastening arch 19 a, 19 b, 19 c has a moreangular shape that assists with anchoring of a valvular prosthesis 100to the stent 10.

The alternative shapes of the closed ends of the retaining and fasteningarches (16, 19) accommodates the enlarged heads 31 of shortenedauxiliary arches 18 a, 18 b, 18 c. The enlarged head 31 enables theauxiliary arches to be used to support the valve material 100, as wellas providing additional radial force. The heads 31 include fasteningholes 12 for additional attachment of the prosthetic valve 100 whichfurther stabilizes the prosthetic valve 100 attached to the stent. Theadditional fastening holes 12 also reduce the likelihood ofmiss-aligning the valve 100 within the stent 10 and minimize anylongitudinal movement of the valve 100 once the endoprosthesis 1 hasbeen implanted. In addition and as already discussed in relation to theretaining arches 16 a, 16 b, 16 c, an enlarged contact area is providedwith the widened head portions 31, which improves the anchorage of thestent 10 at the implantation site while minimizing the risk of damage tothe vessel wall.

As can be seen from the cutting pattern of FIG. 3, the upper armportions of the respective retaining arches 16 a, 16 b, 16 c areconnected to the lower region 14 of the associated fastening portion 11,while the upper arm portions of the auxiliary arches 18 a, 18 b, 18 care connected to the central region of the associated fastening portion11. In this way, it is possible to form secure connections between thearms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of the retaining arches 16a, 16 b, 16 c, and between the arms 18 a′, 18 a″, 18 b′, 18 b″, 18 c′,18 c″ of the auxiliary arches 18 a, 18 b, 18 c and the fastening portion11 without having to enlarge the overall size of the stent 10.

A yet further difference between the stent of the third embodiment andthe stents of the first and second embodiments is the inclusion ofnotches 26. As shown in FIG. 3, the notches 26 are located at the lowerend of the fastening portion 11 and are formed in the arms of theauxiliary arches 18 a, 18 b, 18 c and the retaining arches 16 a, 16 b,16 c. To ensure the strength of the stent is maintained, the notches areshaped in the arms rather than being cut out of the arms. The notches 26function as additional guides and anchoring points for suture thread orwire.

To accommodate the notches 26, the auxiliary arches 18 a, 18 b, 18 cextend from the fastening portion 11 mid-way along the length of thefastening portion 11, rather than from the lower end of the fasteningportion 11. This provides each auxiliary arch 18 a, 18 b, 18 c withsufficient flexibility that would otherwise be lacking from a shorterauxiliary arch.

FIG. 4 shows flat roll-out view of a stent 10 according to a fourthembodiment of the invention, the flat roll-out view depicted in FIG. 4corresponding to the two-dimensional projection of a cutting patternsuitable for the manufacture of a stent 10 according to a fourthembodiment of the invention.

The fourth embodiment of the stent 10 is similar to the thirdembodiment. However, the stent of the fourth embodiment includesadditional fastening holes 12 a provided for fastening a valvularprosthesis. Specifically, the additional fastening holes 12 a are at thelower end 17 p of the first connecting webs 17. The additional fasteningholes 12 a are configured as eyelets on the first connecting webs 17between the fastening portion 11 and the connecting portion 22. It is ofcourse conceivable that the additional fastening holes 12 a are notconfigured as eyelets but are directly formed in the first connectingwebs. The additional fastening holes 12 a enable the upper region of avalvular prosthesis to be additionally secured to the stent 10.

The size of the additional fastening holes 12 a may be adapted to thethickness of particular thread or wire used to fasten the valvularprosthesis to the stent 10. The cross-sectional shape of the additionalfastening holes 12 a may also be adapted to the cross-sectional shape ofthe thread or wire used for fastening the valvular prosthesis. Due tothe presence of a number of additional fastening holes 12 a for fixingthe valvular prosthesis to the cardiac valve stent, the fasteningposition of the valvular prosthesis to the cardiac valve stent can beprecisely defined.

As an alternative to fastening holes 12 a, the same region of the stent10 may be provided with one or more additional notches. These notchesperform the same function as the fastening holes 12 a and assist withadditional anchoring of a prosthetic valve within the stent 100.

A stent 10 according to the fifth embodiment of the invention is shownin FIGS. 5a-c with the stent 10 in its expanded state, FIGS. 5a and 5bshow side views of the stent 10, while FIG. 5c shows a plan view on theupper end 3 of the stent 10. FIG. 5d shows a flat roll-out view of astent according to the fifth embodiment of the invention, whichcorresponds to a two-dimensional projection of a cutting patternsuitable for the manufacture of a stent according to the fifthembodiment of the invention, the stent being cut integrally from aportion of tube, in particular a metal tube.

The stent 10 according to the fifth embodiment is comparable instructural and functional respect to the stent of the third embodiment.In particular, the stent 10 of the fifth embodiment similarly has atotal of three positioning arches 15 a, 15 b, 15 c, which againundertake the function of automatic positioning of the stent 10 in theplane of the valve of the pulmonary valve or the aortic valve. As inother embodiments of the stent 10, the positioning arches 15 a, 15 b, 15c have a radiused head portion 20, which engages in the pockets of thenative heart valve H being treated during positioning of the stent 10 atthe implantation site in the heart (see FIG. 18a ).

A total of three retaining arches 16 a, 16 b, 16 c and three fasteningarches 19 a, 19 b, 19 c are also provided.

The fifth embodiment stent 10 differs from the stent of the thirdembodiment in that further notches 26 a are provided in addition to thefastening holes 12 in the fastening portion 11. As can be seen in FIG.5d , a series of notches 26 a are provided which serve as additionalanchoring means for the tissue component(s) of the valvular prosthesis100 and guides for the suture thread or wire. These additional notches26 a also minimize movement of the suture thread or wire therebyreducing wear on the thread or wire by rubbing on the first connectingweb 17 when the endoprosthesis 1 is implanted. The additional notches 26a also ensure that the upper region of a valvular prosthesis can befastened firmly to the cardiac valve stent 10 allowing minimal movementof the prosthesis thereby further minimizing the likelihood of wearinduced by friction on the suture thread or wire.

It is conceivable of course that the additional notches 26 a are adaptedto the thickness of the suture thread or wire. In particular, theadditional notches 26 a may be radiused to minimize damage to the suturethread or wire.

The fifth embodiment of the stent 10 also includes radial arches 32 a,32 b, 32 c extending from the positioning arches 15 a, 15 b, 15 ctowards the upper end 3 of the stent 10. As is shown most clearly inFIGS. 5a and 5b , the stent 10 has three radial arches 32 a, 32 b, 32 c,with each arch 32 a, 32 b, 32 c located between the two arms 15 a, 15a′, 15 b, 15 b′, 15 c, 15 c′ of each positioning arch 15 a, 15 b, 15 c.Each radial arch 32 a, 32 b, 32 c has a shape that is roughly inverse toeach positioning arch 15 a, 15 b, 15 c and extends in the oppositedirection to each one of the positioning arches 15 a, 15 b, 15 c.

As can be seen in particular in the cutting pattern shown in FIG. 5d ,each arm 32′, 32″ of a radial arch 32 merges at about the mid-point ofthe length of the stent 10 into an arm 15 a′, 15 a″, 15 b′, 15 b″, 15c′, 15 c″ of an opposing positioning arch 15 a, 15 b, 15 c.

The two arms 32′, 32″ of each radial arch 32 a, 32 b, 32 c are connectedtogether at the upper end 3 of the stent 10 by means of a radiusedconnecting portion or head. This head is not only radiused but alsowidens at the tip so that the head abuts against the interior wall ofthe vessel over as large a contact area as possible when the stent 10 isin its expanded and implanted state.

The heads of each radial arch 32 a, 32 b, 32 c also serve as additionalmeans by which the stent 10 may be retained in a catheter before andduring implantation and/or to recapture the stent after implantation.

FIG. 5c shows a perspective plan view from the upper end 3 of the stent10 and illustrates that the radial arches 32 a, 32 b, 32 c areprogrammed so that they extend in a radial direction outside thecircumference of the stent 10 when the stent 10 is in its expandedstate. In this way an increased contact force can be applied to thevessel wall by the upper end region of the stent 10. This, in turn,allows an increased security in the fixing of the stent 10 in situ,thereby reducing the likelihood of migration of the stent. Therefore, inits expanded state, in addition to the clamping effect of thepositioning arches, the stent 10 of the fifth embodiment is secured inplace on implantation via radial forces exerted by the retaining arches16 a, 16 b, 16 c, the auxiliary arches 18 a, 18 b, 18 c and the radialarches 32 a, 32 b, 32 c, all of which project outwards in a radialdirection from the circumference of the stent 10.

It can be seen from the cutting pattern shown in FIG. 5d that the radialarches 32 a, 32 b, 32 c do not project in the longitudinal direction Lof the stent 10 beyond the plane in which the catheter retaining means23 or the fastening means with fastening eyelets 24 are situated. Thisensures that the catheter retaining means 23 can co-operate withcorresponding means within a suitable implantation catheter withoutinterference from the heads of the radial arches 32 a, 32 b, 32 c.Indeed, as explained above, the heads themselves can be used asadditional catheter retaining means or additional means to effectexplanation of the stent 10.

In principle, the stent 10 may have more than three radial arches 32 inorder to increase the radial contact force further. It is also possibleto provide barb elements on all or some of the radial arches 32 a, 32 b,32 c, for example, to allow a still better anchoring of the stent 10 atthe implantation site.

A stent 10 according to a sixth embodiment of the invention is shown inFIGS. 6a-d and FIGS. 6f-i . FIGS. 6a-c show various side views the stent10 in its expanded state while a flat roll-out view of a stent accordingto the sixth embodiment is shown in FIG. 6d , said roll-out viewcorresponds to a two-dimensional projection of a cutting patternsuitable for the manufacture of the stent according to the sixthembodiment.

FIG. 6e shows a side view of an endoprosthesis for treating a narrowedcardiac valve or a cardiac valve insufficiency, where the endoprosthesiscomprises a cardiac valve stent which is similar to the sixth embodimentof the invention for holding a valvular prosthesis. In detail, FIG. 6eshows a valvular prosthesis 100 attached to a stent 10 as an example onhow to fix a valvular prosthesis 100 to a stent 10. This example isapplicable to the stent embodiments described herein.

FIG. 6f show a side view of an endoprosthesis for treating a narrowedcardiac valve or a cardiac valve insufficiency, where the endoprosthesiscomprises the cardiac valve stent according to the sixth embodiment ofthe invention for holding a valvular prosthesis.

FIGS. 6g and 6h show various perspective detail views of theendoprosthesis shown in FIG. 6f . FIG. 6i shows a plan view of the lowerend of the endoprosthesis shown in FIG. 6 f.

As in the embodiments previously described, the stent 10 of the sixthembodiment is again configured as a one-piece structure cut from aportion of tube, in particular from a metal tube, the cutting patternbeing shown as a two-dimensional projection in FIG. 6 d.

The sixth embodiment of the stent 10 is in principle similar instructure and function with respect to the fifth embodiment. To avoidrepetition, reference is therefore made to the above description of thefifth embodiment. In particular, essentially U-shaped or V-shaped radialarches 32 a, 32 b, 32 c are likewise provided to increase the radiallyacting contact force in the upper region of the stent 10.

The sixth embodiment differs from the fifth embodiment in that fixingbridges 27 with additional fastening portions 11 a are provided foradditional fastening of the tissue component(s) of the valvularprosthesis. The presence of fixing bridges 27 with additional fasteningportions 11 a is a particular advantage when a valve constructed from asheet of biological material, such as pericardium, is used as a valvularprosthesis, i.e. a valvular prosthesis which is made up of severalpieces of material. When pericardial valves are used, care must be takento ensure that the pericardial material can be securely attached to thestent 10. For this reason, the stent 10 according to the sixthembodiment has a total of three fixing bridges 27 each comprisingadditional fastening portions 11 a. Each fixing bridge 27 is attached toone of the first connecting webs 17 and extends in the direction of thelower end 2 of the stent 10.

The additional fastening portions 11.a provided on the fixing bridges 27have yet more fastening holes 12 b and/or other fastening means, forexample notches 26 b, to anchor a thread or a thin wire which is used tofastened the pericardial material or the valvular prosthesis to thestent 10 allowing minimal, preferably no, movement of the valvularprosthesis. It is of course conceivable to provide fastening holes orfastening eyelets, the diameter of which is adapted to the thickness ofthe thread or wire used for fastening the valvular prosthesis. Ingeneral, the fastening holes 12 b or notches 26 b should be radiused tominimize wear of the thread or the wire induced by friction so far as ispossible.

Reference is made to FIGS. 6e and 6f which show side views of anendoprosthesis 1 for treating a narrowed cardiac valve or a cardiacvalve insufficiency. In the embodiment depicted in FIG. 6f , the stent10 corresponds to a stent pursuant the sixth embodiment of the inventionfor holding a valvular prosthesis 100. The description of how thevalvular prosthesis 100 is fixed to the stent 10 with respect to thesixth embodiment is also applicable to a stent 10 according to the otherembodiments described herein.

The valvular prosthesis 100 comprises at least one leaflet 102 (see FIG.6i ) made from a biological or synthetic material. In particular, FIG.6e shows a side view of a endoprosthesis 1, whereby the cardiac stent 10is shown in a partially expanded state. FIG. 6f shows a side view of aendoprosthesis 1, whereby the cardiac stent 10 is shown in a fullyexpanded state. FIGS. 6g-i show various perspective detail views of theendoprosthesis 1 depicted in FIG. 6f . In detail, FIG. 6g is aperspective detail view of the head portion 30 of a retaining arch 16 aand FIG. 6h is a perspective detail view of an additional fasteningportion 11 a. FIG. 6i is a plan view of the lower end 2 of theendoprosthesis 1 shown in FIG. 6 f.

To ensure that minimal longitudinal displacement of the valvularprosthesis 100 affixed to stent 10 can occur relative stent 10, evenduring the peristaltic movement of the heart and the blood vessel inwhich stent 10 is deployed, the stent 10 according to the sixthembodiment of the invention comprises a plurality of fastening portions11 extending in the longitudinal direction L of stent 10. In addition,the stent 100 according to the sixth embodiment is provided withadditional fastening portions 11 a, each of which is attached to one ofthe first connecting webs 17 and extends in the direction of the lowerend 2 of the stent 10. By means of both the fastening portions 11 andthe additional fastening portions 11 a the tissue component(s) of thevalvular prosthesis 100 is affixed to the stent 10.

In detail, the tissue component(s) of the valvular prosthesis 100 isfastened to the stent 10 by means of a thread 101 or a thin wire whichis guided through each respective fastening hole 12, 12 b of thefastening portions 11 and the additional fastening portions 11 a,respectively. This allows fixing of the valvular prosthesis 100 to thestent 10 at a precise predefined position relative to the stent 10. Byproviding of a plurality of fastening holes 12 to anchor the valvularprosthesis 100 to the stent 10, precise positioning of the valvularprosthesis 100 on stent 10 is achieved.

Reference is made to FIG. 6e which shows an endoprosthesis 1 with astent 10 which is a variant of the stent according to the sixthembodiment of the invention. The stent 10 shown in FIG. 6e is not yetfully expanded. An endoprosthesis 1 with a fully-expanded stent 10according to the sixth embodiment of the invention is shown in FIG. 6 f.

The stent 10 according to the present invention is—as will be describedin detail below with reference to the illustrations of FIGS. 18a-c—advanced in the collapsed state in minimally-invasive fashion via aninsertion catheter system either from the apex cordis (i.e. transapical)or through the femoral artery and the aortic arch (i.e. transfemoral) tothe site of implantation at the heart. During the insertion procedure,the stent 10 with the valvular prosthesis 100 affixed thereto isaccommodated in the tip K of the catheter system in the collapsed state(cf. FIG. 18a ). Upon reaching the site of implantation at the heart,the stent 10 with the valvular prosthesis 100 affixed thereto issequentially released by the selective manipulating of parts of theproximal side K of the delivery portion of the catheter system.

It is important to note that the insertion procedure shown in FIGS.18a-c is an insertion procedure by which an endoprosthesis 1 is insertedthrough the femoral artery and the aortic arch (i.e. transfemoral) tothe site of implantation at the heart. However, the invention is notlimited to the specific delivery access described with reference toFIGS. 18a-c . Rather, for implanting the endoprosthesis 1 variousapproaches may be used, for example a transapical approach for treatingthe aortic valve by which the endoprosthesis is brought to the site ofimplantation at the heart from the apex cordis (i.e. a transapicalapproach).

In detail, during a first release step, the proximal side K of thedelivery portion of the insertion catheter system is manipulated suchthat the positioning arches 15 a-c of stent 10 are released while theremaining parts of the stent 10, in particular the retaining arches 16a, 16 b, 16 c, the auxiliary arches 18 a-c and the radial arches 32 a-care still in their collapsed state (cf. FIG. 18a ). The positioningarches 15 a-c released during the first release step expand and spreadradially outward. The expanded positioning arches 15 a-c can then beinserted into the pockets T of the patient's native cardiac valve H bysuitably moving the proximal side K of the delivery portion of thecatheter system (cf. FIG. 18a ).

In the second release step which follows, the proximal side K of thedelivery portion of the insertion catheter system is manipulated suchthat the arches forming the lower end 2 of the stent 10 (auxiliaryarches 18 a-c and retaining arches 16 a, 16 b, 16 c) are released whilethe upper end 3 of the stent 10 is however still firmly affixed to theproximal side K of the delivery portion of the catheter system and isnot released (cf. FIG. 18b ).

The positioning arches 15 a-c disposed on stent 10 and also theretaining arches 16 a, 16 b, 16 c may be curved in convex and archedfashion in the lower direction; i.e. toward the lower end 2 of stent 10,whereby such a rounded form may reduce injuries to the artery as well asfacilitate the unfolding during the self-expansion. Such a design mayenable an easier insertion of the positioning arches 15 a-c into thepockets of the native cardiac valve without correspondingly injuring theneighboring tissue or blood vessels.

In FIG. 6e , the endoprosthesis 1 exhibiting the stent 10 in accordancewith one embodiment of the invention with a valvular prosthesis 100affixed to said stent 10 is shown in a state after the second releasestep in which only the upper end 3 with the catheter retaining means 23is firmly connected to the tip K of the insertion catheter system whilethe remaining portions of the stent 10 have already been released andradially expanded. It can be seen from the FIG. 6e illustration that dueto the self-expansion of the retaining arches 16 a, 16 b, 16 c and theauxiliary arches 18 a-c, the valvular prosthesis 100 affixed thereto hasalready expanded (at least partly).

As shown in FIG. 6e , the upper end section 3 of stent 10 is stillaccommodated in a sleeve-like portion P within a delivery portion of acatheter system (not explicitly shown in FIG. 6e ). This remains thecase until the unfolding and positioning of the valvular prosthesis 100has taken place to the extent that it can be checked for functionality.

If the functional test shows that the valvular prosthesis 100satisfactorily functions, the sleeve-like portion P can be pulled backdistally so that also the upper end section 3 of stent 10 with thecatheter retaining means 23 is fully released (cf. FIG. 18c ).

It can further be seen from the FIG. 6e illustration how the valvularprosthesis 100 can be affixed to the stent 10 by means of threads 101. Apericardial valvular prosthesis 100 is used in the embodiment depictedwhich is sewn to fastening holes 12 b of a fixing bridge 27 extendingbetween two neighboring retaining arches 16 a, 16 b. See FIG. 6c andFIG. 6f . The valvular prosthesis 100 may be virtually tubular with asubstantially circular cross-section. At the lower end 2 of the stent10, the valvular prosthesis 100 exhibits a bead 105. This bead 105,which is annular in the plan view of endoprosthesis 1, is formed byturning the lower end of the valvular prosthesis 100 inside out byrolling it over on itself. As shown in FIG. 6e , the annular bead 105 isoveredged by thread 101. The annular bead 105 may be of a differentconfiguration.

The annular bead 105 at the lower end of the valvular prosthesis 100 mayprovide a secure anchoring of the peripheral area of the valvularprosthesis 100 to the blood vessel in the implanted state of theendoprosthesis 1, even given the peristaltic motion, and thus mayprovide a secure seal relative the vascular wall.

The annular bead 105 at the lower end of the valvular prosthesis 100 mayalso provide good contact and more uniform structure at the lower endsection 2 of the stent 10 to more evenly distribute the radial forcesneeded to anchor the endoprosthesis 1 in its implanted state. In thisregard, sealing and preventing leakage after implantation of theendoprosthesis 1 can be achieved. Over time, tissue growth will furthersecure the endoprosthesis 1 to prevent any movement relative to theblood vessel in the implanted state of the endoprosthesis 1 or leakage.When implanting the endoprosthesis 1 in a native blood vessel anyleakage between the peripheral area of the annular bead 105 and thevascular wall is sealed by a good contact and radial pressure betweenthe endoprosthesis 1 and the diseased native valve annulus. Accordingly,the bead-shaped area 105 provides a secure seal, particularly alsoduring the filling phase of the heart cycle (diastole).

FIG. 6i likewise shows a plan view of the lower end 2 of theendoprosthesis 1 depicted for example in FIG. 6f , i.e. a view from theinflow side of the endoprosthesis shown in FIG. 6f , whereby the stent10 for the endoprosthesis 1 is shown in its fully-expanded state.

As shown in FIG. 6i , the leaflets 102 of the valvular prosthesis 100are in a semi-closed position, as is the case in the beginning of thediastole of the heart.

As shown in FIGS. 6f and 6g in detail, the fixing bridges 27 with theadditional fastening portions 11 a also have notches 26 b to anchor thethread or thin wire which is used to fasten the pericardial material orthe tissue component(s) of the valvular prosthesis 100 to the stent 10allowing minimal, preferably no, movement of the valvular prosthesis.Further, the auxiliary arches 18 a-c are used as fastening means foranchoring the valvular prosthesis 100 to the stent 10.

It can also be noted from FIGS. 6f and 6g that lower part of thevalvular prosthesis 100 is turned inside out such as to form acircumferential flap in which the respective head portions 30′ of thefastening arches 19 a-c and the respective head portions 31 of theauxiliary arches 18 a-c engage. The valvular prosthesis 100 is thusfastened to the stent 10 with minimal play such that relative movementbetween the stent 10 and the valvular prosthesis 100 due to theperistaltic motion of the heart can be effectively prevented when theendoprosthesis 1 is implanted.

A seventh embodiment of the inventive stent 10 will be described in thefollowing with reference to FIGS. 7a-c . Here, FIGS. 7b and 7c each showside views of the fully-expanded stent 10 according to the seventhembodiment.

Except for the lower end section, the stent 10 according to the seventhembodiment essentially corresponds to the stent according to the sixthembodiment of the present invention described above with reference toFIGS. 6a-d and FIGS. 6f -i.

Hence, the stent 10 according to the seventh embodiment has also a totalof three positioning arches 15 a, 15 b, 15 c, which again undertake thefunction of automatic positioning of the stent 10 in the plane of thevalve of the pulmonary valve or the aortic valve. As in otherembodiments of the stent 10, the positioning arches 15 a, 15 b, 15 chave a radiused head portion 20, which engages in the pockets of thenative heart valve H being treated during positioning of the stent 10 atthe implantation site in the heart (see FIG. 18a ).

A total of three retaining arches 16 a, 16 b, 16 c is also provided.Contrary to the stent design of the sixth embodiment, however, in thestent design according to the seventh embodiment, the two arms 16 a′, 16a″, 16 b′, 16 b″, 16 c′, 16 c″ of each retaining arch 16 a, 16 b, 16 care not connected to each other via a connecting portion which hasalmost an O-shaped configuration. Rather, in the seventh embodiment, thelower end section of each arm of the retaining arches 16 a, 16 b, 16 cmerges into an annular collar 40, which will be described in more detailbelow.

As in the sixth embodiment of the present invention, the stent designaccording to the seventh embodiment is also provided with fixing bridges27 with additional fastening portions 11 a for additional fastening ofthe tissue component(s) of a valvular prosthesis or parts of a valvularprosthesis. Each fixing bridge 27 is attached to one of the firstconnecting webs 17 and extends in the direction of the lower end 2 ofthe stent 10. The additional fastening portions 11 a provided on thefixing bridges 27 have yet more fastening holes 12 b and notches 26 b toanchor a thread or a thin wire which is used to fastened the pericardialmaterial or the tissue component(s) of the valvular prosthesis to thestent 10 allowing minimal, preferably no, movement of the valvularprosthesis. It is of course conceivable to provide fastening holes orfastening eyelets, the diameter of which is adapted to the thickness ofthe thread or wire used for fastening the tissue component(s) of thevalvular prosthesis.

The seventh embodiment of the stent 10 also includes radial arches 32 a,32 b, 32 c extending from the positioning arches 15 a, 15 b, 15 ctowards the upper end 3 of the stent 10. As is shown most clearly inFIGS. 7b and 7c , the stent 10 has three radial arches 32 a, 32 b, 32 c,with each arch 32 a, 32 b, 32 c located between the two arms 15 a, 15a′, 15 b, 15 b′, 15 c, 15 c′ of each positioning arch 15 a, 15 b, 15 c.Each radial arch 32 a, 32 b, 32 c has a shape that is roughly inverse toeach positioning arch 15 a, 15 b, 15 c and extends in the oppositedirection to each one of the positioning arches 15 a, 15 b, 15 c.

Since in the implanted state of the endoprosthesis 1, substantial forcesact on the valvular prosthesis 100 during the filling phase of the heartcycle (diastole), which are transmitted to the stent affixed with thevalvular prosthesis 100, the secure anchoring of the stent 10 with thevalvular prosthesis 100 affixed thereto at the site of implantation mayof distinct importance. The seventh to eleventh embodiments of the stent10 described in the following incorporate further measures which can beprovided additionally to the above-described embodiments of retainingarches, auxiliary arches and radial arches which may more securelyanchor of stent 10, endoprosthesis 1 respectively, at the site ofimplantation and which may prevent a positional displacement ofendoprosthesis 1.

In detail, at least one annular collar 40, which forms the lower end 2of the stent 10, is provided in accordance with the seventh embodimentas an additional anchoring measure for the stent 10 depicted in FIGS. 7b-c.

FIG. 7a shows a flat roll-out view of another cardiac valve stentaccording to the seventh embodiment of the invention. The roll-out viewdepicted in FIG. 7a corresponds to a two-dimensional projection of acutting pattern which my be used in the production of a cardiac valvestent according to the seventh embodiment in order to enable a cardiacvalve stent according to the seventh embodiment to be integrally cutfrom a section of tube, in particular a metal tube.

Apart from the connection of the annular collar 40 to the stent body,the stent design depicted in FIG. 7a corresponds to the design of thestents 10 shown in FIGS. 7b-c . In detail, according to the stent designdepicted in the roll-out view of FIG. 7a , in the modification of theseventh embodiment, the stent is provided with fastening arches 19 a, 19b, 19 c and retaining arches 16 a, 16 b, 16 c. As shown in the flatroll-out view according to FIG. 7a , a fastening arch 19 a, 19 b, 19 cand a retaining arch 16 a, 16 b, 16c is allocated to each positioningarch 15 a, 15 b, 15 c, and each retaining arch 16 a, 16 b, 16 c isconnected to a neighboring retaining arch by means of an auxiliary arch18 a, 18 b, 18 c. A fastening portion with a specific number offastening holes 12 is configured in each arm 16 a′, 16 a″, 16 b′, 16 b″,16 c′, 16 c″ of retaining arch 16 a, 16 b, 16 c.

Contrary to the stent design of, for example, the sixth embodiment,however, in the stent design depicted in FIG. 7a , neither the two arms16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of each retaining arch 16 a, 16b, 16 c nor the two arms 19 a′, 19 a″, 19 b′, 19 b″, 19 c′, 19 c″ ofeach fastening arch 19 a, 19 b, 19 c are respectively connected to eachother via a connecting portion which has almost an O-shapedconfiguration. Rather, in the stent design depicted in FIG. 7a , thelower end section of each arm of the retaining arches 16 a, 16 b, 16 con the one hand and the lower end section of each arm of the fasteningarches 19 a, 19 b, 19 c on the other hand respectively merges into anannular collar 40 having an identical configuration compared with theannular collar of the stent design depicted in FIGS. 7b -c.

Contrary to the stent design depicted in FIG. 7a , the stent 10 shown inFIGS. 7b-c is provided with an annular collar 40 which is merelyconnected to each or a part of the lower end sections of the respectiveretaining arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of retainingarches 16 a, 16 b, 16 c since the stent 10 shown in FIGS. 7b-c is notprovided with fastening arches as the stent design depicted in FIG. 7a .On the other hand, however, the stent design depicted in FIG. 7a isprovided with an annular collar 40 which is connected to each or a partof the lower end sections of the respective retaining arms 16 a′, 16 a″,16 b′, 16 b″, 16 c′, 16 c″ of retaining arches 16 a, 16 b, 16 c as wellas to each or a part of the lower end sections of the respective arms 19a′, 19 a″, 19 b′, 19 b″, 19 c′, 19 c″ of the fastening arches 19 a-c.

In general, however, the stent 10 of the seventh embodiment an annularcollar 40 wherein the annular collar 40 may also be connected to each ora part of the lower end sections of the respective arms 18 a′, 18 a″, 18b′, 18 b″, 18 c′, 18 c″ of the auxiliary arches 18 a, 18 b, 18 c, as canbe seen in particular from the flat roll-out view pursuant to FIG. 7a orthe side view pursuant to FIG. 7b or the perspective view pursuant toFIG. 7 c.

The annular collar 40 exhibits a plurality of supporting webs 41 whichrun parallel to the longitudinal axis of the stent 10 in thenon-expanded state of said stent 10 and are inter-connected bytransversal webs 42 (cf. FIG. 7a ). In the expanded state of stent 10,the supporting webs 41 and the transversal webs 42 form a rhomboidal orserpentine-like annular collar 40 which abuts against the vascular wallin the implanted state of endoprosthesis 1, stent 10 respectively. FIGS.7b and 7c show the annular collar 40 in the expanded state.

The annular collar 40 serves as a supporting body through which theradial forces developing due to the self-expansion are transmitted tothe vascular wall. Since a relatively large contact area of the stent 10interacts with the vascular wall, and because of the rhomboidal orserpentine structure to the annular collar 40, there may be a decreasedrisk of injury to the artery or the tissue despite the increased radialforces.

Accordingly, not only the rigidity of the stent 10 can be increasedafter its self-expansion by the providing of the annular collar 40, butalso the anchorage of the stent 10 in the implanted state can beimproved or strengthened. Additionally, the annular cross-sectionalshape to annular collar 40 increases the seal between the vascular walland the endoprosthesis 1.

Such an annular collar 40 is advantageously configured as aself-expandable supporting structure which advantageously effects aneven further improved anchoring of the stent 10 at the site ofimplantation due to its radially-outward-acting contact pressure and itsdesign such that a displacing of the stent 10 with the valvularprosthesis 100 can be further prevented.

An eighth embodiment of the inventive stent 10 is shown in FIGS. 8a-c .In detail, FIG. 8b and FIG. 8c each show a stent 10 of the eighthembodiment in a side view, whereby the stent 10 is fully expanded. FIG.8a shows a flat roll-out view of a cardiac valve stent according to theeighth embodiment of the invention, said roll-out view depicted in FIG.8a corresponding to a two-dimensional projection of a cutting patternapplicable to manufacturing a cardiac valve stent according to theeighth embodiment to cut the cardiac valve stent integrally from aportion of a tube, in particular a metal tube.

Except for the upper end section, the stent 10 according to the eighthembodiment essentially corresponds to the stent according to the fifthembodiment of the present invention described above with reference toFIGS. 5a -d.

Hence, the stent 10 of the eighth embodiment similarly has a total ofthree positioning arches 15 a, 15 b, 15 c, which again undertake thefunction of automatic positioning of the stent 10 in the plane of thevalve of the pulmonary valve or the aortic valve. As in otherembodiments of the stent 10, the positioning arches 15 a, 15 b, 15 chave a radiused head portion 20, which engages in the pockets of thenative heart valve H being treated during positioning of the stent 10 atthe implantation site in the heart (see FIG. 18a ).

A total of three retaining arches 16 a, 16 b, 16 c and three fasteningarches 19 a, 19 b, 19 c are also provided.

Furthermore, in the eighth embodiment stent 10, further notches 26 a areprovided in addition to the fastening holes 12 in the fastening portion11 which serve as additional anchoring means for the tissue component(s)of the valvular prosthesis 100 and guides for the suture thread or wire.These additional notches 26 a also minimize movement of the suturethread or wire thereby reducing wear on the thread or wire by rubbing onthe first connecting web 17 when the endoprosthesis 1 is implanted. Theadditional notches 26 a also ensure that the upper region of a valvularprosthesis can be fastened firmly to the cardiac valve stent 10 allowingminimal movement of the prosthesis thereby further minimizing thelikelihood of wear induced by friction on the suture thread or wire.

A total of three retaining arches 16 a, 16 b, 16 c and three fasteningarches 19 a, 19 b, 19 c are also provided.

In contrast to the seventh embodiment (cf. FIG. 7a-c ), however, thelower end 2 of the stent 10 remains unchanged in the eighth embodimentwhile an upper annular collar 40′ is formed at the upper end 3 of thestent 10. As FIGS. 8b and 8c show, the annular collar 40′ is constructedof supporting webs 41 and transversal webs 42 and forms a rhombicsupporting structure in the expanded state.

To be seen from the illustration of the cutting pattern according toFIG. 8a is that the upper annular collar 40′ utilized in the eighthembodiment is connected to the upper head portions of radial arches 32a, 32 b, 32 c. On the other hand, the upper annular collar 40′ isconnected to the second connecting web 25 such that it is disposed at adistance from the plane in which the catheter retaining means 23 arepositioned in the expanded state (cf. FIGS. 8b, 8c ). Specifically, theannular collar 40′ in the eighth embodiment is situated between theplane in which the catheter retaining means 23 lies and the plane inwhich the connecting portion 22 of the two arms of neighboringpositioning arches 15 a-c lies. To this end, the connecting web 25is—compared to the connecting web in the fifth embodiment—configured tobe somewhat longer.

Since the upper annular collar 40′ utilized in the eighth embodiment iscomparable to the lower annular collar 40 utilized in the seventhembodiment in terms of functioning. In particular, the upper annularcollar 40′ provides good anchoring to prevent migration of theendoprosthesis in its implanted state and a uniform distribution ofthese radial forces.

The following will reference FIGS. 9a and 9b in describing a ninthembodiment of the stent 10 according to the invention. FIG. 9b therebyshows a perspective view of a stent 10 according to the ninth embodimentin the expanded state. FIG. 9a shows a flat roll-out view of a cardiacvalve stent according to the ninth embodiment of the invention. Theroll-out view depicted in FIG. 9a corresponds to a two-dimensionalprojection of a cutting pattern applicable to manufacturing a cardiacvalve stent according to the ninth embodiment in order to cut thecardiac valve stent integrally from a portion of a tube, in particular ametal tube.

Since an upper annular collar 40′ is likewise formed at the upper end 3of the stent 10, the stent 10 in accordance with the ninth embodiment issimilar to the previously-described stent according to FIGS. 8a-c(eighth embodiment). In contrast to the eighth embodiment, the upperannular collar 40′ in the ninth embodiment is configured to be longer inthe longitudinal direction of the stent 10. Specifically, a comparisonof FIG. 9b and FIG. 8b shows that in the ninth embodiment, two rhombicannular bodies lying atop one another are employed as the annular collar40′. This may increase the radial contact force that the stent 10 exertsfrom its upper end 3. A correspondingly elongated connecting web 25 isagain utilized in the embodiment according to FIGS. 9a -b.

FIG. 10 shows a flat roll-out view of a cardiac valve stent 10 inaccordance with a tenth embodiment of the invention, said roll-out viewalso being a two-dimensional projection of a cutting pattern which canbe used to cut a cardiac valve stent 10 in accordance with a tenthembodiment as one integral piece from a portion of a tube, in particulara metal tube.

As also with the eighth embodiment described above with reference toFIGS. 8a-b and the ninth embodiment described above with reference toFIGS. 9a-b , the tenth embodiment of the inventive stent 10 essentiallycorresponds to the embodiment described with reference to FIGS. 5a -d.

In contrast, for example, to the eighth embodiment (cf. FIG. 8a-c ),however, the upper end 3 of the stent 10 remains unchanged in the tenthembodiment while a lower annular collar 40 is formed at the lower end 2of the stent 10. As FIG. 10 shows, the annular (lower) collar 40 is alsoconstructed of supporting webs 41 and transversal webs 42 and forms arhombic supporting structure in the expanded state.

To be seen from the illustration of the cutting pattern according toFIG. 10 is that the lower annular collar 40 utilized in the tenthembodiment is connected to the lower head portions of retaining arches16 a, 16 b, 16 c, of fastening arches 19 a, 19 b, 19 c, and of auxiliaryarches 18 a, 18 b, 18 c. On the other hand, the lower annular collar 40is connected to the retaining arches 16 a, 16 b, 16 c, of fasteningarches 19 a, 19 b, 19 c, and of auxiliary arches 18 a, 18 b, 18 c suchthat it is disposed at a distance from the plane in which the catheterretaining means 23 is positioned in the expanded state.

Since the lower annular collar 40 utilized in the tenth embodiment iscomparable to the lower annular collar 40 utilized in the seventhembodiment in terms of functioning, and is not further described forclarification purposes.

FIG. 11 shows a flat roll-out view of a cardiac valve stent 10 inaccordance with a eleventh embodiment of the invention.

Except for the upper and lower end section, the stent 10 according tothe eleventh embodiment is similar to the stent according to the fifthembodiment of the present invention described above with reference toFIGS. 5a -d.

Hence, the stent 10 according to the eleventh embodiment has also atotal of three positioning arches 15 a, 15 b, 15 c, which againundertake the function of automatic positioning of the stent 10 in theplane of the valve of the pulmonary valve or the aortic valve. As inother embodiments of the stent 10, the positioning arches 15 a, 15 b, 15c have a radiused head portion 20, which engages in the pockets of thenative heart valve H being treated during positioning of the stent 10 atthe implantation site in the heart (see FIG. 18a ).

A total of three retaining arches 16 a, 16 b, 16 c and three fasteningarches 19 a, 19 b, 19 c are also provided.

The eleventh embodiment of the stent 10 also includes radial arches 32a, 32 b, 32 c extending from the positioning arches 15 a, 15 b, 15 ctowards the upper end 3 of the stent 10. As is shown in FIG. 11, thestent 10 has three radial arches 32 a, 32 b, 32 c, with each arch 32 a,32 b, 32 c located between the two arms 15 a, 15 a′, 15 b, 15 b′, 15 c,15′ of each positioning arch 15 a, 15 b, 15 c. Each radial arch 32 a, 32b, 32 c has a shape that is roughly inverse to each positioning arch 15a, 15 b, 15 c and extends in the opposite direction to each one of thepositioning arches 15 a, 15 b, 15 c.

The eleventh embodiment of the stent (cf. FIG. 11) differs from thefifth embodiment of the present invention described above with referenceto FIGS. 5a-d in that two annular collars 40, 40′, which forms the lowerand upper ends 2, 2′ of the stent 10, are provided in accordance withthe eleventh embodiment as an additional anchoring measure for the stent10. As in the seventh embodiment described above with reference to FIGS.7a-c , the lower annular collar 40 is connected to the lower endsections of the respective retaining arms 16 a′, 16 a″, 16 b′, 16 b″, 16c′, 16 c″ of retaining arches 16 a, 16 b, 16 c and the lower endsections of the respective arms 19 a′, 19 a″, 19 b′, 19 b″, 19 c′, 19 c″of the fastening arches 19 a-c, as can be seen in particular from thecutting pattern pursuant FIG. 11. On the other hand, the upper annualcollar 40′ utilized in the eleventh embodiment is connected to the upperhead portions of radial arches 32 a, 32 b, 32 c. In detail, the annualcollar 40′ in the eleventh embodiment is situated between the plane inwhich the catheter retaining means 23 lies and the plane in which theconnecting portion 22 of the two arms of neighboring positioning arches15 a-c lies.

As already described with respect to the seventh to tenth embodiment ofthe present invention, the upper and lower annular collars 40, 40′exhibits a plurality of supporting webs 41 which run parallel to thelongitudinal axis of the stent 10 in the non-expanded state of saidstent 10 and are interconnected by transversal webs 42 (cf. FIG. 11).Again, in the expanded state of stent 10, the supporting webs 41 and thetransversal webs 42 form a rhomboidal or serpentine-like annular collars40, 40′ which abuts against the vascular wall in the implanted state ofendoprosthesis 1, stent 10 respectively.

A comparison of FIG. 11 with the cutting patterns according to FIGS. 8aand 9a shows that the stent 10 in accordance with the eleventhembodiment of the invention basically proceeds from the stent 10according to the eighth embodiment (cf. FIGS. 8a-c ), whereby for thepurpose of improved anchoring, an additional (lower) annular collar 40is formed at the lower end 2 of the stent 10. This additional lowerannular collar corresponds substantially to the lower annular collaremployed in the seventh embodiment (cf. FIGS. 7a-c ). To avoidrepetition, reference is made to the foregoing remarks with respect tothe seventh and eighth embodiments.

Naturally, the annular collar 40 or 40′ can in principle also bearranged in a plane in which the valvular prosthesis is situated. It isfurthermore not imperative for the annular collar 40 to be connected toall the end sections of the retaining arches 16 a, 16 b, 16 c or theauxiliary fastening arches 19 a-c respectively. Nor does the upperannular collar 40′ necessarily have to be connected to all the endsections of the radial arches 32.

FIG. 12 shows a flat roll-out view of a cardiac valve stent inaccordance with a twelfth embodiment of the invention. The roll-out viewdepicted in FIG. 12 could also be used as a cutting pattern formanufacturing a stent according to the twelfth embodiment. A side viewor a perspective view of a stent according to the twelfth embodiment isnot shown in the drawings.

Elements in FIG. 12 that are generally similar to previously describedelements have the same reference numbers compared with the referencenumbers in FIGS. 1 to 11 previously used for the similar elements.

In principle, the stent according to the twelfth embodiment is similarto the stent of the fifth embodiment already described with reference toFIGS. 5a-d . To avoid repetition, reference is therefore made to theabove description of the fifth embodiment.

Briefly summarized, the stent of the twelfth embodiment similarly has atotal of three positioning arches 15 a, 15 b, 15 c, which againundertake the function of automatic positioning of the stent in theplane of the pulmonary valve or the aortic valve. As in otherembodiments of the stent, the positioning arches 15 a, 15 b, 15 c have aradiused head portion 20, which engages in the pockets of the nativeheart valve H being treated during positioning of the stent at theimplantation site in the heart (see FIG. 18a ).

Also, the stent of the twelfth embodiment is provided with a total ofthree retaining arches 16 a, 16 b, 16 c. According to the cuttingpattern depicted in FIG. 12, however, in the stent design according tothe twelfth embodiment, fastening arches may be omitted. It is, ofcourse, possible to provide the stent structure of the twelfthembodiment with such fastening arches as described in connection with,for example, the stent of the fifth embodiment.

In addition, essentially U-shaped or V-shaped radial arches 32 a, 32 b,32 c are likewise provided to increase the radially acting contact forcein the upper region 3 of the stent. The radial arches 32 a, 32 b, 32 cof the stent according to the twelfth embodiment extend from thepositioning arches 15 a, 15 b, 15 c towards the upper end 3 of thestent. According to the cutting pattern depicted in FIG. 12, the stentof the twelfth embodiment has three radial arches 32 a, 32 b, 32 c, witheach arch 32 a, 32 b, 32 c located between the two arms 15 a, 15 a′, 15b, 15 b′, 15 c, 15 c′ of each positioning arch 15 a, 15 b, 15 c. Eachradial arch 32 a, 32 b, 32 c has a shape that is roughly inverse to eachpositioning arch 15 a, 15 b, 15 c and extends in the opposite directionto each one of the positioning arches 15 a, 15 b, 15 c. Each arm 32′,32″ of a radial arch 32 merges at about the mid-point of the length ofthe stent into an arm 15 a′, 15 a″, 15 b′, 15 b″, 15 c′, 15 c″ of anopposing positioning arch 15 a, 15 b, 15 c.

The two arms 32′, 32″ of each radial arch 32 a, 32 b, 32 c are connectedtogether at the upper end 3 of the stent by means of a radiusedconnecting portion or head. This head is not only radiused but alsowidens at the tip so that the head abuts against the interior wall ofthe vessel over as large a contact area as possible when the stent ofthe twelfth embodiment is in its expanded and implanted state.

The heads of each radial arch 32 a, 32 b, 32 c also serve as additionalmeans by which the stent of the twelfth embodiment may be retained in acatheter before and during implantation and/or to recapture the stentafter implantation.

In addition to retaining arches 16 a, 16 b, 16 c, the stent of thetwelfth embodiment further comprises auxiliary arches 18 a, 18 b, 18 c,which likewise exert a radially-acting contact force against the wall ofthe blood vessel in the implanted state of stent, thereby furtherimproving anchoring of stent at the site of implantation.

To recapitulate, providing retaining arches 16 a, 16 b, 16 c on the onehand and auxiliary arches 18 a, 18 b, 18 c on the other hand results ina radial force being exerted on the vascular wall by the respectivelower end portions of these arches. This provides both a secure seal ofa valvular prosthesis affixed to the stent relative the vascular wall,as well as a secure anchoring of the stent, at the site of implantationin the heart.

As can be seen from the cutting pattern according to FIG. 12, the stentof the twelfth embodiment comprises a total of three essentiallyU-shaped or V-shaped auxiliary arches 18 a, 18 b, 18 c which are closedtowards the lower end 2 of the stent. Each auxiliary arch 18 a, 18 b, 18c connects a first retaining arch 16 a, 16 b, 16 c with a secondretaining arch neighboring the first retaining arch.

Although not explicitly illustrated in the cutting pattern according toFIG. 12, the radial arches 32 a, 32 b, 32 c are preferably programmed sothat they extend in a radial direction outside the circumference of thestent when the stent of the twelfth embodiment is in its expanded state.In this way, an increased contact force can be applied to the vesselwall by the upper end region of the stent when the stent of the twelfthembodiment is in its expanded and implanted state. This, in turn, mayprovide an increased security in the fixing of the stent in situ,thereby reducing the likelihood of migration of the stent. Therefore, inits expanded and implanted state, in addition to the clamping effect ofthe positioning arches, the stent of the twelfth embodiment is securedin place on implantation via radial forces exerted by the retainingarches 16 a, 16 b, 16 c, the auxiliary arches 18 a, 18 b, 18 c and theradial arches 32 a, 32 b, 32 c, all of which project outwards in aradial direction from the circumference of the stent.

It can be seen from the cutting pattern shown in FIG. 12 that the radialarches 32 a, 32 b, 32 c do not project in the longitudinal direction Lof the stent beyond the plane in which the catheter retaining means 23or the fastening means with fastening eyelets 24 are situated. Thisensures that the catheter retaining means 23 can co-operate withcorresponding means within a suitable implantation catheter withoutinterference from the heads of the radial arches 32 a, 32 b, 32 c.Indeed, as explained above, the heads themselves can be used asadditional catheter retaining means or additional means to effectexplanation of the stent of the twelfth embodiment.

As in the fifth embodiment, the stent according to the twelfthembodiment may have more than three radial arches 32 in order toincrease the radial contact force further. It is also possible toprovide barb elements on all or some of the radial arches 32 a, 32 b, 32c, for example, to anchor the stent at the implantation site.

As already indicated, the stent according to the twelfth embodimentexhibits a structure integrally cut from a portion of tube, and inparticular from a metal tube. As in other stent embodiments of thepresent invention, in the stent according to the twelfth embodiment, aretaining arch 16 a, 16 b, 16 c is allocated to each positioning arch 15a, 15 b, 15 c, and each retaining arch 16 a, 16 b, 16 c is connected toa neighboring retaining arch by means of an auxiliary arch 18 a, 18 b,18 c. Also, at least one fastening portion 11 with a specific number offastening holes 12 is configured in each arm 16 a′, 16 a″, 16 b′, 16 b″,16 c′, 16 c″ of retaining arch 16 a, 16 b, 16 c.

The stent of the twelfth embodiment differs, in particular, from thestent of the fifth embodiment in that the stent according to the twelfthembodiment is not provided with additional notches denoted, for example,in FIGS. 5a-d with reference number “26 a”. Rather, instead ofadditional notches, the stent according to the twelfth embodimentcomprises first and second additional fastening portions 11 a, 11 b foradditional fastening of the tissue component(s) of a valvular prosthesisor parts of a valvular prosthesis.

In detail, first additional fastening portions 11 a are provided foradditional fastening of the tissue component(s) of the valvularprosthesis or parts of a valvular prosthesis. These first additionalfastening portions 11 a are provided with auxiliary fastening holes 12 band/or other fastening means, for example notches, to anchor a thread ora thin wire which is used to fastened the pericardial material or thetissue component(s) of the valvular prosthesis to the stent allowingminimal, preferably no, movement of the valvular prosthesis. The firstadditional fastening portions 11 a are arranged between the first andsecond arms 16 a″, 16 b′; 16 b″, 16 c′; 16 c″, 16 a′ of two neighboringretaining arches 16 a, 16 b, 16 c and extend from the respective lowerends 17 d of the first connecting webs 17 in the direction of the lowerend 3 of the stent, the first connecting webs 17 being provided with thealready mentioned second additional fastening portions lib.

In addition to the first additional fastening portions 11 a, the stentaccording to the twelfth embodiment further comprises second additionalfastening portions 11 b. In detail, each first connecting web 17 of thestent according to the twelfth embodiment is provided with at least onesecond additional fastening portion 11 b, said at least one secondadditional fastening portion 11 b being a portion which comprisesadditional auxiliary fastening holes 12 c and/or other fastening means.The at least one second additional fastening portion 11 b extendsessentially in the longitudinal direction L of stent according to thetwelfth embodiment.

A comparison of the cutting pattern depicted in FIG. 12 with the cuttingpattern depicted, for example, in FIG. 5d , shows that each of the firstconnecting webs 17 of the stent according to the twelfth embodiment isprovided with one second additional fastening portion 11 b. In thisregard, the stent according to the twelfth embodiment is provided withsecond additional fastening portions 11 b, the upper end portionsthereof open into connecting portion 22 between the two arms 15 a′, 15a″, 15 b′, 15 b″, 15 c′, 15 c″ of two neighboring positioning arches 15a, 15 b, 15 c.

On the other hand, in the stent design according to the twelfthembodiment, the first connecting webs 17 with the second additionalfastening portions 11 b each exhibit a structure that diverges at therespective lower end portions of the first connecting webs 17 to giveway to the respective arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ oftwo neighboring retaining arches 16 a, 16 b, 16 c.

In detail, the first connecting webs 17 with the second additionalfastening portions 11 b connect with connecting portions 22 via theirupper ends 17 d and with the upper ends of the first additionalfastening portions 11 a on the one hand as well as with the upper endsof the respective arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of theretaining arches 16 a, 16 b, 16 c via their lower ends 17 p.

The additional auxiliary fastening holes 12 c and/or other fasteningmeans of the second additional fastening portions 11 b serve foranchoring a thread or a thin wire which is used to fastened thepericardial material or the tissue component(s) of the valvularprosthesis to the stent allowing minimal, preferably no, movement of thevalvular prosthesis.

With regard to the first and second additional fastening portions 11 a,11 b of the stent according to the twelfth embodiment, it is of courseconceivable to provide fastening holes 12 b, 12 c or fastening eyelets,the diameter of which is adapted to the thickness of the thread or wireused for fastening the tissue components) of the valvular prosthesis.Preferably, the fastening holes 12 b, 12 c or fastening eyelets shouldbe radiused to minimize wear of the thread or the wire induced byfriction so far as is possible.

The presence of first and second additional fastening portions 11 a, 11b with auxiliary and additional auxiliary fastening holes 12 b, 12 c isa particular advantage when a valve constructed from a sheet ofbiological material, such as pericardium, is used as an endoprosthesis,including a valvular prosthesis which is made up of several pieces ofmaterial.

When pericardial valves are used, care must be taken to ensure that thepericardial material can be securely attached to the stent. For thisreason, the stent according to the twelfth embodiment has a total ofthree first additional fastening portions 11 a each comprising auxiliaryfastening holes 12 b, as well as a total of three second additionalfastening portions 11 b each comprising additional auxiliary fasteningholes 12 c.

Apart from the above described difference, the stent of the twelfthembodiment differs particularly from the stent of the fifth embodimentin that the stent according to the twelfth embodiment is provided withat least one so-called “leaflet guard arch”.

In detail, according to the cutting pattern depicted in FIG. 12, thestent of the twelfth embodiment is provided with a total of threeleaflet guard arches 50 a, 50 b, 50 c, each comprising two leaflet guardarms. It can be seen from the cutting pattern shown in FIG. 12 that, inthe structure of the stent according to the twelfth embodiment, aleaflet guard arch 50 a, 50 b, 50 c is provided in between eachpositioning arch 15 a, 15 b, 15 c. Hence, in the stent according to thetwelfth embodiment, a leaflet guard arch 50 a, 50 b, 50 c is allocatedto each positioning arch 15 a, 15 b, 15 c.

Each leaflet guard arch 50 a, 50 b, 50 c has a substantially U-shaped orV-shaped structure which is closed to the lower end 2 of stent. Inparticular, each leaflet guard arch 50 a, 50 b, 50 c has a shape that isroughly similar to the shape of the positioning arch 15 a, 15 b, 15 c inbetween the corresponding leaflet guard arch 50 a, 50 b, 50 c isarranged. Furthermore, each leaflet guard arch 50 a, 50 b, 50 c extendsin the same direction as the positioning arch 15 a, 15 b, 15 c.

In the stent design of the twelfth embodiment, each arm of a leafletguard arch 50 a, 50 b, 50 c merges at about the mid-point of the lengthof an arm of a radial arch 32 a, 32 b, 32 c into the arm of an opposingradial arch 32 a, 32 b, 32 c. It can be seen from the cutting patternshown in FIG. 12 that, according to the stent design of the twelfthembodiment, the leaflet guard arches 50 a, 50 b, 50 c do not project inthe longitudinal direction L of the stent approximately beyond the planein which the lower end portion of the at least one fastening portion 11configured in each arm 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ ofretaining arch 16 a, 16 b, 16 c are situated. The leaflet guard arches50 a, 50 b, 50 c may extend lower than the lower end of the fasteningportion 11 so long as the positioning arches 15 a, 15 b, 15 c can deployduring the expansion of the stent 10 and that the leaflet guard arches50 a, 50 b, 50 c do not interfere during deployment.

In this regard, during the insertion procedure, the stent with avalvular prosthesis affixed thereto can be sequentially released uponreaching the site of implantation at the heart wherein, during a firstrelease step, the proximal side K of the delivery portion of theinsertion catheter system is manipulated such that the positioningarches 15 a-c of stent are released while the remaining parts of thestent, in particular the leaflet guard arches 50 a, 50 b, 50 c, theretaining arches 16 a, 16 b, 16 c, the auxiliary arches 18 a-c and theradial arches 32 a-c are still in their collapsed state (cf. FIG. 18a ).The positioning arches 15 a-c released during the first release stepexpand and spread radially outward. The expanded positioning arches 15a-c can then be inserted into the pockets T of the patient's nativecardiac valve H by suitably moving the proximal side K of the deliveryportion of the catheter system (cf. FIG. 18a ).

In the second release step which follows, the proximal side K of thedelivery portion of the insertion catheter system is manipulated suchthat the leaflet guard arches 50 a, 50 b, 50 c are released while theremaining parts of the stent, in particular the retaining arches 16 a,16 b, 16 c, the auxiliary arches 18 a-c and the radial arches 32 a-c arestill in their collapsed state. The leaflet guard arches 50 a, 50 b, 50c released during the second release step expand and spread radiallyoutward. The expanded leaflet guard arches 50 a, 50 b, 50 c push thediseased leaflets, i.e. the leaflets of the native (diseased) cardiacvalve, to the neighboring tissue or blood vessel.

In the third release step which follows, the proximal side K of thedelivery portion of the insertion catheter system is manipulated suchthat the arches forming the lower end 2 of the stent (auxiliary arches18 a-c and retaining arches 16 a, 16 b, 16 c) are released while theupper end 3 of the stent is however still firmly affixed to the proximalside K of the delivery portion by using a sleeve-like portion and is notreleased (cf. FIG. 18b ). Also, the radial arches 32 a-c are still intheir compressed state.

If a functional test shows that the valvular prosthesis 100 affixed tothe stent satisfactorily functions, the sleeve-like portion at theproximal side K of the catheter system can be distally pushed further inthe direction to the lower end section of the stent 10 in order torelease the radial arches 32 a, 32 b and 32 c.

Then, also the upper end section 3 of the stent 10 with the catheterretaining means 23 is fully released, as shown in FIG. 18c . This can beobtained by distally pushing the sleeve-like portion at the deliveryportion of the catheter system further in the direction to the lower endsection 3 of the stent 10.

The positioning arches 15 a-c disposed on the stent and also theretaining arches 16 a, 16 b, 16 c may be curved in convex and archedfashion in the direction to the lower end section of the stent; i.e.toward the lower end 2 of the stent, whereby such a rounded form mayreduce injuries to the artery as well as facilitate the unfolding duringthe self-expansion. Such a design may enable an easier insertion of thepositioning arches 15 a-c into the pockets of the native cardiac valvewithout correspondingly injuring the neighboring tissue or bloodvessels.

Although not explicitly illustrated in the cutting pattern according toFIG. 12, the leaflet guard arches 50 a, 50 b, 50 c are preferablyprogrammed so that they extend in a radial direction outside thecircumference of the stent when the stent of the twelfth embodiment isin its expanded state. In this way, an increased contact force can beapplied to the leaflets of the native (diseased) cardiac valve when thestent of the twelfth embodiment is in its expanded and implanted state.This, in turn, allows an increased security in the fixing of the stentin situ.

When the stent is in its expanded and implanted state, the leaflet guardarches 50 a, 50 b, 50 c actively keep the diseased leaflets, i.e. theleaflets of the native cardiac valve, from impinging the leaflet tissueof the valvular prosthesis attached to the stent, when the positioningarches 15 a, 15 b, 15 c are placed outside, the native leaflets. Inaddition, the leaflet guard arches 50 a, 50 b, 50 c may also provideadditional anchoring and securing against migration. This feature isunique compared to the cage known from the prior art stent designs whichare not provided with positioning arches to push the diseased leafletsout of the way.

In addition to the above described features, the stent design accordingto the twelfth embodiment further differs from the stent design of, forexample, the fifth embodiment in that the stent according to the twelfthembodiment is provided with additional arches. In the expanded state ofthe stent, each of these additional arches (hereinafter “extra arches”)has a substantially U-shaped or V-shaped structure which is closed tothe lower end 2 of stent. In particular, each extra arch extends in thesame direction as the retaining arch 16 a, 16 b, 16 c and the auxiliaryarch 18 a, 18 b, 18 c and positioned therebetween.

In detail, according to the cutting pattern depicted in FIG. 12, thestent of the twelfth embodiment is provided with a total of six extraarches 60 a-f, each comprising two arms. These extra arches 60 a-f exerta radially-acting contact force against the wall of the blood vessel inthe implanted state of stent, thereby further improving anchoring of thestent at the site of implantation.

Providing retaining arches 16 a, 16 b, 16 c and auxiliary arches 18 a,18 b, 18 c on the one hand and extra arches 60 a-f on the other hand mayprovide a radial force being exerted on the vascular wall by therespective lower end portions of these arches. This provides both asecure seal of a valvular prosthesis affixed to stent relative thevascular wall, as well as a secure anchoring of the stent, at the siteof implantation in the heart.

As can be seen from the cutting pattern according to FIG. 12, the stentof the twelfth embodiment comprises a total of three essentiallyU-shaped or V-shaped extra arches 60 a-f which are closed towards thelower end 2 of the stent. Each extra arch connects a retaining arch 16a, 16 b, 16 c with an auxiliary arch 18 a, 18 b, 18 c neighboring theretaining arch 16 a, 16 b, 16 c. Hence, in the stent according to thetwelfth embodiment, one extra arch is allocated to each retaining arch16 a, 16 b, 16 c and each auxiliary arch 18 a, 18 b, 18 c.

This stent design particularly provides a total of twelve arches(retaining arches 16 a, 16 b, 16 c, auxiliary arches 18 a, 18 b, 18 cand extra arches 60 a-f) substantially uniformly distributed around thelower end region 2 of stent, each of which press against the vascularwall and effectively hold the stent in position in the expanded andimplanted state of stent. Hence, in a top plan view of the lower endregion 2 of the expanded stent (not explicitly shown), the lower endregion 2 of the stent exhibits a polygonal structure having a pluralityof vertices formed from the individual arms 16 a′, 16 a″, 16 b′, 16 b″,16 c′, 16 c″ of the retaining arches 16 a, 16 b, 16 c, the individualarms 18 a′, 18 a″, 18 b′, 18 b″, 18 c′, 18 c″ of the auxiliary arches 18a, 18 b, 18 c, as well as from the individual arms of the extra arches60 a, 60 b, 60 c, 60 d, 60 e, 60 f. In this regard, the stent accordingto the twelfth embodiment has a lower end section 2 with a continuousdesign that may provide a substantially uniform radial force to helpsecure the stent in its implanted stage and resist migration. Such aradial force may also help to minimize the risk of leakage.

On the other hand, the extra arches 60 a-f of the stent according to thetwelfth embodiment may not increase the overall length of the stent.Hence, although this stent design may provide uniform radial force, therisk of contacting with the nerve bundles and heart block if the lowerend portion of the stent is below the annulus at the location where thenerve bundles enter, may be reduced.

A stent 10 according to a thirteenth embodiment of the invention isshown in FIGS. 13b and 13c . In detail, FIGS. 13b and 13c show variousside views the stent 10 in its expanded state while a flat roll-out viewof a stent 10 according to the thirteenth embodiment is shown in FIG.13a . The roll-out view depicted in FIG. 13a corresponds to atwo-dimensional projection of a cutting pattern suitable for themanufacture of a stent according to the thirteenth embodiment. Elementsin FIGS. 13a-c that are generally similar to previously describedelements have the same reference numbers.

As in the embodiments previously described, the stent 10 of thethirteenth embodiment is configured as a one-piece structure cut from aportion of tube, in particular from a metal tube, the cutting patternbeing shown as a two-dimensional projection in FIG. 13 a.

The thirteenth embodiment of the stent 10 is similar in structure andfunction with respect to the previously described twelfth embodiment. Toavoid repetition, reference is therefore made to the above descriptionof the twelfth embodiment.

Hence, the stent 10 according to the thirteenth embodiment is providedwith corresponding retaining arches 16 a, 16 b, 16 c. One retaining arch16 a, 16 b, 16 c is allocated to each positioning arch 15 a, 15 b, 15 c,wherein each retaining arch 16 a, 16 b, 16 c is connected to aneighboring retaining arch by means of an auxiliary arch 18 a, 18 b, 18c. Also, according to the thirteenth embodiment of the stent 10, atleast one fastening portion 11 with a number of fastening holes 12 isconfigured in each arm 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of theretaining arches 16 a, 16 b, 16 c.

In addition to the at least one fastening portion 11, the stent 10according to the thirteenth embodiment also comprises first and secondadditional fastening portions 11 a, 11 b for additional fastening of avalvular prosthesis or parts of a valvular prosthesis. In this regard,the stent 10 has a configuration with an enhanced number of fasteningportions 11, 11 a, 11 b to attach the material of a valvular prosthesis.

As in the twelfth embodiment, the stent 10 depicted in FIG. 13b or 13 cis also provided with a total of three leaflet guard arches 50 a, 50 b,50 c, each of said leaflet guard arches 50 a, 50 b, 50 c comprising twoleaflet guard arms. It can be seen from the cutting pattern shown inFIG. 13a that, a leaflet guard arch 50 a, 50 b, 50 c is provided inbetween each positioning arch 15 a, 15 b, 15 c. Hence, in the stentdesign according to the thirteenth embodiment, one leaflet guard arch 50a, 50 b, 50 c is allocated to each positioning arch 15 a, 15 b, 15 c.

As shown in FIG. 13b or 13 c, each arm of a leaflet guard arch 50 a, 50b, 50 c merges at about the mid-point of the length of an arm of aradial arch 32 a, 32 b, 32 c into the arm of an opposing radial arch 32a, 32 b, 32 c. Again, as in the stent design according to the twelfthembodiment, the leaflet guard arches 50 a, 50 b, 50 c of the stent 10according to the thirteenth embodiment project in the longitudinaldirection L of the stent approximately to the plane in which the lowerend portion of the at least one fastening portion 11 configured in eacharm 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of retaining arch 16 a, 16b, 16 c is placed. In this regard, during the insertion procedure, thestent 10 of the thirteenth embodiment can be sequentially released asalready described in connection with the stent design of the twelfthembodiment.

As previously mentioned, the respective arms of the leaflet guard arches50 a, 50 b, 50 c merge at about the mid-point of the length of an arm ofa radial arch 32 a, 32 b, 32 c into the arm of an opposing radial arch32 a, 32 b, 32 c. Contrary to the twelfth embodiment, however, in thestent design of the thirteenth embodiment, the arms 32 a′, 32 a″, 32 b′,32 b″, 32 c′, 32 c″ of the radial arches 32 a, 32 b, 32 c do not mergeinto an arm 15 a′, 15 a″, 15 b′, 15 b″, 15 c′, 15 c″ of an opposingpositioning arch 15 a, 15 b, 15 c. According to the stent design of thethirteenth embodiment, the respective arms 32 a′, 32 a″, 32 b′, 32 b″,32 c′, 32 c″ of the radial arches 32 a, 32 b, 32 c are not directlyconnected with the arms 15 a′, 15 a″, 15 br, 15 b″, 15 c′, 15 c″ of anopposing positioning arch 15 a, 15 b, 15 c.

Rather, the leaflet guard arms of the stent design according to thethirteenth embodiment are directly connected with one of the secondconnecting webs 25, i.e. with one of the webs which connect theconnecting portions 22 of the stent 10 with the catheter retaining means23. As already mentioned above, the connecting portions 22 of the stent10 is used for connecting each two adjoining arms 15 b″, 15 c; 15 c″, 15a′; 15 a″, 15 b′ of two neighboring positioning arches 15 b, 15 c, 15 a.In this regard, the deployment of the positioning arches 15 a, 15 b, 15c is enhanced without releasing the leaflet guard arches 50 a, 50 b, 50c until the positioning arches 15 a, 15 b, 15 c are placed behind thediseased leaflets in the valve pockets.

As can be seen in particular from the two-dimensional cutting patternaccording to FIG. 13a , the stent design of the thirteenth embodiment isalso provided with a total of six extra arches 60 a-f, each of whichhaving a substantially U-shaped or V-shaped structure which is closed tothe lower end 2 of the stent 10. In particular, each extra arch 60 a-fextends in the same direction as the retaining arch 16 a, 16 b, 16 c andthe auxiliary arch 18 a, 18 b, 18 c, between which the correspondingextra arch 60 a-f is provided.

Referring to FIG. 13b or FIG. 13c , the stent design of the thirteenthembodiment provides a total of twelve arches (retaining arches 16 a, 16b, 16 c, auxiliary arches 18 a, 18 b, 18 c and extra arches 60 a-f)uniformly distributed around the lower end region 2 of stent 10. In theexpanded and implanted stage of the stent 10, this specific structure ofthe lower end section 2 shall press against the vascular wall to holdthe stent 10 in position.

As in the stent design according to the twelfth embodiment, the lowerend region 2 of the stent 10 of the thirteenth embodiment also exhibitsa polygonal structure having eighteen vertices formed from theindividual arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of retainingarches 16 a, 16 b, 16 c, the individual arms 18 a′, 18 a″, 18 b′, 18 b″,18 c′, 18 c″ of the auxiliary arches 18 a, 18 b, 18 c, as well as theindividual arms of the extra arches 60 a-f. In this regard, the stent 10of the thirteenth embodiment has a lower end section 2 with a continuousdesign which may provide substantially uniform radial force to helpsecure the stent 10 in its implanted stage and may help resistmigration. Such a uniform radial force may also help minimize the riskof blood leakage in the expanded and implanted stage of the stent 10 anda valvular prosthesis affixed thereto.

The stent 10 according to the thirteenth embodiment also differs fromthe stent of the twelfth embodiment in that additional fasteningportions are provided at the lower end 2 of the stent 10. In detail,according to FIG. 13b or FIG. 13c , the stent 10 of the thirteenthembodiment is provided with three essentially U-shaped or V-shapedauxiliary arches 18 a, 18 b, 18 c, each of said auxiliary arches 18 a,18 b, 18 c being provided at its lower end section with an additionalfastening portion provided in the head portion 31 of the respectiveauxiliary arches 18 a-18 c.

As can be seen from FIG. 13a , a defined plurality of fastening holes 12d are configured in the respective fastening portions provided in therespective head portions 31 of the auxiliary arches 18 a, 18 b, 18 c.Furthermore, in the stent design of the thirteenth embodiment, therespective arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of eachretaining arch 16 a, 16 b, 16 c extend from the fastening portion 11 tothe lower end 2 of the cardiac valve stent 10 and are connected togetherby means of a connecting portion 30, wherein this connection portion 30is also provided with fastening holes 12 e.

In this regard, the auxiliary arches 18 a, 18 b, 18 c with the fasteningholes 12 d on the one hand and the connection portions 30 with thefastening holes 12 e on the other hand provide for additional fasteningholes 12 d, 12 e at the lower end section 2 of the stent 10, whereinthese additional fastening holes 12 d, 12 e are arranged to be equallydistributed around the continuous design of the lower end section 2 ofthe stent 10. A thread 101 or a thin wire with which a valvularprosthesis 100 is attached to stent 10 may be guided through each of therespective fastening holes 12 d, 12 e.

Hence, the additional fastening holes 12 d, 12 e are provided at thelower end section 2 of the stent 10 for additional fastening of avalvular prosthesis or parts of a valvular prosthesis. The presence ofadditional fastening holes 12 d, 12 e at the lower end section 2 of thestent 10 may provide additional structure to attach the valve skirt ofthe valvular prosthesis and minimize leakage. In addition, theadditional fastening holes 12 d, 12 e at the lower end section 2 of thestent 10 may help keep the skirt of the valvular prosthesis from movingwhen the valve is collapsed into a catheter for implanting the stentwith the valvular prosthesis affixed thereto.

FIG. 14b shows a side view of a stent 10 according to the fourteenthembodiment of the invention, whereby the stent 10 is in its completelyexpanded state. The stent 10 according to the fourteenth embodimentexhibits a structure integrally out from a portion of a tube, inparticular a metal tube. The cutting pattern used to form the design ofthe stent 10 according to the fourteenth embodiment is depicted in atwo-dimensional projection in FIG. 14 a.

Again, elements in FIGS. 14a and 14b that are generally similar topreviously described elements have the same reference numbers.

Except for the structure of the lower end section 2, the stent 10according to the fourteenth embodiment is substantially similar to thestent according to the thirteenth embodiment of the present inventiondescribed above with reference to FIGS. 13a and 13 b.

Hence, the stent 10 according to the fourteenth embodiment has also atotal of three positioning arches 15 a, 15 b, 15 c, which againundertake the function of automatic positioning of the stent 10. As inother embodiments of the stent 10, each of the positioning arches 15 a,15 b, 15 c has a radiused head portion 20, which engages in the pocketsof the native heart valve H being treated during positioning of thestent 10 at the implantation site in the heart (see FIG. 18a ).

The fourteenth embodiment of the stent 10 also includes radial arches 32a, 32 b, 32 c. As is shown most clearly in FIG. 14b , the stent 10 hasthree radial arches 32 a, 32 b, 32 c, with each arch 32 a, 32 b, 32 clocated between the two arms 15 a, 15 a′, 15 b, 15 b′, 15 c, 15 c′ ofeach positioning arch 15 a, 15 b, 15 c. Each radial arch 32 a, 32 b, 32c has a shape that is roughly inverse to each positioning arch 15 a, 15b, 15 c and extends in the opposite direction to each one of thepositioning arches 15 a, 15 b, 15 c.

As in the thirteenth embodiment, in the stent design of the fourteenthembodiment, the respective arms 32 a′, 32 a″, 32 b′, 32 b″, 32 c′, 32 c″of the radial arches 32 a, 32 b, 32 c are not directly connected withthe arms 15 a′, 15 a″, 15 b′, 15 b″, 15 c′, 15 c″ of an opposingpositioning arch 15 a, 15 b, 15 c. Rather, the respective arms 32 a′, 32a″, 32 b′, 32 b″, 32 c′, 32 c″ of the radial arches. 32 a, 32 b, 32 care directly connected to leaflet guard arms which in turn are directlyconnected with one of the second connecting webs 25, i.e. with one ofthe webs which connect the connecting portions 22 of the stent 10 withthe catheter retaining means 23. In this regard, the deployment of thepositioning arches 15 a, 15 b, 15 c is enhanced without releasing theleaflet guard arches 50 a, 50 b, 50 c until the positioning arches 15 a,15 b, 15 c are placed behind the diseased leaflets in the valve pockets.

A total of three retaining arches 16 a, 16 b, 16 c is also provided. Oneretaining arch 16 a, 16 b, 16 c is allocated to each positioning arch 15a, 15 b, 15 c. Also, according to the fourteenth embodiment of theinventive stent 10, at least one fastening portion 11 with a number offastening holes 12 is configured in each arm 16 a′, 16 a″, 16 b′, 16 b″,16 c′, 16 c″ of the retaining arches 16 a, 16 b, 16 c.

In addition to the at least one fastening portion 11, the stent 10according to the fourteenth embodiment also comprises first and secondadditional fastening portions 11 a, 11 b for additional fastening of thetissue component(s) of the valvular prosthesis or parts of a valvularprosthesis. In this regard, the stent 10 has a configuration with anenhanced number of fastening portions 11, 11 a, 11 b to attach thematerial of a valvular prosthesis.

As in the twelfth or thirteenth embodiment, the stent 10 depicted inFIG. 14b is also provided with a total of three leaflet guard arches 50a, 50 b, 50 c, each of said leaflet guard arches 50 a, 50 b, 50 ccomprising two leaflet guard arms. As shown in the cutting patterndepicted in FIG. 14a , a leaflet guard arch 50 a, 50 b, 50 c is providedin between each positioning arch 15 a, 15 b, 15 c, i.e. one leafletguard arch 50 a, 50 b, 50 c is allocated to each positioning arch 15 a,15 b, 15 c.

The respective arms of the leaflet guard arches 50 a, 50 b, 50 c mergesat about the mid-point of the length to the arm of an opposing radialarch 32 a, 32 b, 32 c. As in the thirteenth embodiment, the arms 32 a′,32 a″, 32 b″, 32 b″, 32 c′, 32 c″ of the radial arches 32 a, 32 b, 32 cdo not merge into an arm 15 a′, 15 a″, 15 b′, 15 b″, 15 c′, 15 c″ of anopposing positioning arch 15 a, 15 b, 15 c, because the respective arms32 a′, 32 a″, 32 b′, 32 b″, 32 c′, 32 c″ of the radial arches 32 a, 32b, 32 c are not directly connected with the arms 15 a′, 15 a″, 15 b′, 15b″, 15 c′, 15 c″ of an opposing positioning arch 15 a, 15 b, 15 c.Rather, the leaflet guard arms of the stent design according to thefourteenth embodiment are directly connected with one of the secondconnecting webs 25, i.e. with one of the webs which connect theconnecting portions 22 of the stent 10 with the catheter retaining means23. As already mentioned above, the connecting portions 22 of the stent10 is used for connecting each two adjoining arms 15 b″, 15 c′; 15 c″,15 a′; 15 a″, 15 b′ of two neighboring positioning arches 15 b, 15 c, 15a.

The stent 10 depicted in FIG. 14b is not provided with extra arches atits lower end section 2. Rather, similar to the stent design accordingto the seventh embodiment (cf. FIGS. 7a-c ), the stent 10 of thefourteenth embodiment comprises at least one annular collar 40, whichforms the lower end section 2 of the stent 10. This at least one collar40 serves as an additional anchoring measure for the stent 10 depictedin FIG. 14 b.

The at least one annular collar 40 may be connected to each or a part ofthe lower end sections of the respective arms 16 a′, 16 a″, 16 b′, 16b″, 16 c′, 16 c″ of the retaining arches 16 a, 16 b, 16 c, as can beseen in particular from the cutting pattern pursuant to FIG. 14 a.

The at least one annular collar 40 exhibits a plurality of supportingwebs 41 which run parallel to the longitudinal axis of the stent 10 inthe non-expanded state of said stent 10 and are inter-connected bytransversal webs 42 (cf. FIG. 14a ). In the expanded state of stent 10,the supporting webs 41 and the transversal webs 42 form a rhomboidal orserpentine-like annular collar 40 which abuts against the vascular wallin the implanted state of the stent 10. FIG. 14b shows the annularcollar 40 in the expanded state.

The annular collar 40 serves as a supporting body through which theradial forces developing due to the self-expansion are transmitted tothe vascular wall. Since a relatively large contact area of the stent 10interacts with the vascular wall, and because of the rhomboidal orserpentine structure to the annular collar 40, there may be a decreasedrisk of injury to the artery or the tissue despite the increased radialforces.

It is important to note that a certain amount of radial force is neededto prevent migration of the implanted endoprosthesis 1. Hence, a moreuniform structure of the lower end section of the stent provides a moreuniform distribution of the radial pressure provided by the stent in itsfully expanded state. In this regard, the radial pressure provided bythe stent in its fully expanded state is distributed and there arereduced high contact pressures for the same overall radial force.

Accordingly, not only the rigidity of the stent 10 can be increasedafter its self-expansion by the providing of the annular collar 40, butalso the anchorage of the stent 10 in the implanted state can beimproved or strengthened. Additionally, the annular cross-sectionalshape to annular collar 40 increases the seal between the vascular walland the stent having a vascular prosthesis affixed thereto.

Such an annular collar 40 is advantageously configured as aself-expandable supporting structure which advantageously effects aneven further improved anchoring of the stent 10 at the site ofimplantation due to its radially-outward-acting contact pressure and itsdesign such that a displacing of the stent 10 with a valvular prosthesisaffixed thereto can be further prevented.

The stent 10 depicted in FIG. 14b is not provided with auxiliary archesat the lower end section of the stent body. Rather, instead of auxiliaryarches, the stent 10 according to the fourteenth embodiment comprises astructure of lattice cells 70 formed by a plurality of struts in thearea between the arms of two neighbouring (adjacent) retaining arches 16a, 16 b, 16 c, thereby providing for an additional support of thecommissures of a heart valve prosthesis attached to the stent 10.

In addition, this structure of the lattice cells 70 formed by aplurality of struts in the area between the adjacent arms of twoneighbouring retaining arches 16 a, 16 b, 16 c may provide uniform stentstructure which may minimize blood leakage in the implanted stage of thestent 10 having a heart valve prosthesis attached thereto.

Hence, according to the stent design of the fourteenth embodiment, thelower end section of the annular collar 40 is provided at the lower endsection of the stent body and connected with the stent body via theretaining arches 16 a, 16 b, 16 c on the one hand and the previouslydescribed structure of the lattice cells 70 on the other hand.

Although not shown in FIG. 14b , however, the stent 10 of the fourteenthembodiment may of course also comprise auxiliary arches similar to thestent design previously described with reference to the embodimentsdepicted in FIGS. 7b and 7 c.

It is important to note, however, that the stent 10 depicted in FIG. 14bcomprises a several number of eyelets 12 f uniformly distributed aroundthe lower end section of the annular collar 40. These eyelets 12 f canbe used for fixing a heart valve prosthesis (not shown in FIG. 14b ) tothe stent 10, which may reduce the risk of an axial displacement of theheart valve prosthesis 100 relative to the stent 10.

FIG. 15 shows a flat roll-out view of a cardiac valve stent of stillanother embodiment (fifteenth embodiment). The roll-out view depicted inFIG. 15 corresponds to a two-dimensional projection of a cutting patternwhich can be used to cut a cardiac valve stent of the fifteenthembodiment in accordance with the invention as one integral piece from aportion of a tube, in particular a metal tube. A side view or aperspective view of a stent according to the fifteenth embodiment is notshown in the drawings.

Again, elements in FIG. 15 that are generally similar to previouslydescribed elements have the same reference numbers compared with thereference numbers previously used for the similar elements.

The stent according to the fifteenth embodiment essentially correspondsto the stent of the fourteenth embodiment previously described withreference to FIGS. 14a and 14b . To avoid repetition, reference istherefore made to the above description of the fourteenth embodiment.

In the two-dimensional projection of a cutting pattern according to FIG.15, the corresponding cutting lines for cutting out respective leafletguard arches have been omitted for clarity reasons only. Hence, althoughthe cutting pattern according to FIG. 15 is—for the sake of clarityonly—not provided with corresponding cutting lines, a stent which hasbeen cut in accordance with the design of the fifteenth embodiment mayalso provided with corresponding leaflet guard arches. In particular, itis advantageous when the stent according to the fifteenth embodiment isprovided with a total of three leaflet guard arches, each of said threeleaflet guard arches being constituted by two leaflet guard arms. As thepreviously discussed stent designs according to the twelfth, thirteenthand fourteenth embodiments, a stent of the fifteenth embodiment shallhave a structure with a total of three leaflet guard arches, wherein oneof said three leaflet guard arches is allocated to each positioning arch15 a, 15 b, 15 c and provided in between each positioning arch 15 a, 15b, 15 c.

Furthermore, in the stent design of the fifteenth embodiment each of theleaflet guard arches shall preferably have a substantially U-shaped orV-shaped structure which is closed to the lower end 2 of stent. Inparticular, each leaflet guard arch shall have a shape that is roughlysimilar to the shape of the positioning arch 15 a, 15 b, 15 c in betweenthe corresponding leaflet guard arch is arranged. Furthermore, eachleaflet guard arch shall extend in the same direction as the positioningarch 15 a, 15 b, 15 c in between the corresponding leaflet guard arch isprovided.

The stent design according to the fifteenth embodiment of the inventionis also provided with an annular collar 40 which is arranged at thelower end section of the stent body. As in the stent design according tothe fourteenth embodiment, this at least one collar 40 serves as anadditional anchoring measure for a stent cut from a portion of a tube byusing the cutting pattern depicted in FIG. 15.

According to the cutting pattern depicted in FIG. 15, the at least oneannular collar 40 is connected to the head portions 30 provided at thelower end sections of the respective arms 16 a′, 16 a″, 16 b′, 16 b″, 16c′, 16 c″ of the retaining arches 16 a, 16 b, 16 c. As can be seen fromthe cutting pattern pursuant to FIG. 15, the at least one annular collar40 exhibits a plurality of supporting webs 41 which run parallel to thelongitudinal axis L of the stent in the non-expanded state of said stentand are inter-connected by transversal webs 42. As in the stent designaccording to the fourteenth embodiment, in the expanded state of thestent, the supporting webs 41 and the transversal webs 42 will form arhomboidal or serpentine-like annular collar 40 which abuts against thevascular wall in the implanted state of the stent.

The technical effects which can be obtained by the at least one collar40 provided at the lower end section 2 of the stent have already beendescribed in connection with the stent of the fourteenth embodiment ofthe invention. Hence, in order to avoid repetitions, reference is madeto the previously discussed aspects.

The stent design according to the fifteenth embodiment differs from thestent design according to the fourteenth embodiment in that at the lowerend section of every second supporting web 41 of the annular collar 40an eyelet 12 f as an additional fastening means is provided. In thisregard, the eyelets 12 f are more uniformly distributed around the lowerend section of the annular collar 40, thereby providing a more uniformfixation of a heart valve prosthesis to the stent. Hence, the risk of anaxial displacement of the heart valve prosthesis relative to the stentmay be further reduced.

As in the stent design according to the previously described fourteenthembodiment, the stent design of the fifteenth embodiment is furtherprovided with a structure of lattice cells 70 formed by a plurality ofstruts in the area between the arms of two neighbouring (adjacent)retaining arches 16 a, 16 b, 16 c. As depicted in the cutting pattern ofFIG. 15, the struts which are forming the structure of lattice cells 70are respectively connected to the arms of the retaining arches 16 a, 16b, 16 c. In this regard, an additional support of the commissures of aheart valve prosthesis attached to the stent is provided.

The stent design of the fifteenth embodiment differs from the previouslydescribed stent designs in that the stent according to the fifteenthembodiment is not provided with first additional fastening portions arearranged between the first and second arms 16 a″, 16 b′; 16 b″, 16 c′;16 c″, 16 a′ of two neighboring retaining arches 16 a, 16 b, 16 c andextend from the respective lower ends 17 d of the first connecting webs17 in the direction of the lower end 3 of the stent.

Rather, according to the stent design of the fifteenth embodiment, therespective arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of theretaining arches 16 a, 16 b, 16 c are provided with a number ofadditional fastening portions 11 c, each having a number of additionalfastening holes 12 a provided for fastening the tissue component(s) of avalvular prosthesis. Specifically, the additional fastening portions 11c are separated from each other and distributed over the length of eacharm 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of the retaining arches 16a, 16 b, 16 c. The additional fastening holes 12 a are directly formedin the additional fastening portions 11 c. It is of course conceivablethat the additional fastening holes 12 a are not formed in the arms 16a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of the retaining arches 16 a, 16b, 16 c but are configured as eyelets. The additional fastening holes 12a enable the upper region of a valvular prosthesis to be additionallysecured to the stent.

The size of the additional fastening holes 12 a may be adapted to thethickness of particular thread or wire used to fasten the valvularprosthesis to the stent. The cross-sectional shape of the additionalfastening holes 12 a may also be adapted to the cross-sectional shape ofthe thread or wire used for fastening the valvular prosthesis. Due tothe presence of a number of additional fastening holes 12 a for fixingthe valvular prosthesis to the cardiac valve stent, the fasteningposition of the valvular prosthesis to the cardiac valve stent can beprecisely defined.

As an alternative to fastening holes 12 a, the same region of the stent10 may be provided with one or more additional notches. These notchesperform a similar function as the fastening holes 12 a and assist withadditional anchoring of a prosthetic valve within the stent.

A stent 10 according to a sixteenth embodiment of the invention is shownin FIGS. 16b to 16g . In particular, FIG. 16b is a first perspectiveside view of a cardiac valve stent according to the sixteenth embodimentof the invention, whereby the cardiac valve stent 10 is shown in itsexpanded state. Second and third side views of the cardiac valve stent10 in its expanded state are shown in FIGS. 16c and 16 d.

On the other hand, FIG. 16e shows a plan view of the upper end of thecardiac valve stent 10 according to the sixteenth embodiment of theinvention in its expanded state.

A flat roll-out view of a stent according to the sixteenth embodiment isshown in FIG. 16 a.

FIG. 16f shows a side view of an endoprosthesis for treating a narrowedcardiac valve or a cardiac valve insufficiency, where the endoprosthesiscomprises a cardiac valve stent which is similar to the fifteenthembodiment of the invention for holding a valvular prosthesis. Indetail, FIG. 16f shows a valvular prosthesis 100 attached to a stent 10as an example on how to fix a valvular prosthesis 100 to a stent 10.This example is similarly applicable to the other stent embodimentsdescribed herein.

FIG. 16g shows a side view of an endoprosthesis for treating a narrowedcardiac valve or a cardiac valve insufficiency, where the endoprosthesiscomprises the cardiac valve stent according to the sixteenth embodimentof the invention for holding a valvular prosthesis.

As in the embodiments previously described, the stent 10 of thesixteenth embodiment is again configured as a one-piece structure cutfrom a portion of tube, in particular from a metal tube, the cuttingpattern being shown as a two-dimensional projection in FIG. 16 a.

Also, the stent design according to the sixteenth embodiment of theinvention is also provided with an annular collar 40 which is arrangedat the lower end section of the stent body. As in the stent designaccording to the fourteenth or fifteenth embodiment, this at least onecollar 40 serves as an additional anchoring measure for a stent cut froma portion of a tube by using the cutting pattern depicted in FIG. 15.

The sixteenth embodiment of the stent 10 is similar in structure andfunction with respect to the fifteenth embodiment. To avoid repetition,reference is therefore made to the above description of the fifteenthembodiment. In particular, essentially U-shaped or V-shaped radialarches 32 a, 32 b, 32 c are likewise provided to increase the radiallyacting contact force in the upper region of the stent 10.

In addition, the stent 10 according to the sixteenth embodiment isprovided with corresponding retaining arches 16 a, 16 b, 16 c. Oneretaining arch 16 a, 16 b, 16 c is allocated to one of the positioningarches 15 a, 15 b, 15 c. Also, according to the sixteenth embodiment ofthe inventive stent 10, a number of additional fastening portions 11 cwith a number of additional fastening holes 12 a is configured in eacharm 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of the retaining arches 16a, 16 b, 16 c.

In addition to the additional fastening portions 11 c, the stent 10according to the sixteenth embodiment also comprises second additionalfastening portions 11 b for additional fastening of the tissuecomponent(s) of a valvular prosthesis or parts of a valvular prosthesis.As already discussed with respect to the twelfth embodiment, each firstconnecting web 17 of the stent is provided with at least one secondadditional fastening portion 11 b, said at least one second additionalfastening portion 11 b being a portion which comprises additionalauxiliary fastening holes 12 c and/or other fastening means. The atleast one second additional fastening portion 11 b extends essentiallyin the longitudinal direction L of stent according to the twelfthembodiment.

In this regard, the stent 10 according to the sixteenth embodiment has aconfiguration with a number of fastening portions 11, 11 b to attach thematerial of a valvular prosthesis.

As in the thirteenth embodiment of the invention, the stent 10 depictedin FIGS. 16b-g may also be provided with leaflet guard arches, whereinone leaflet guard arch may be provided in between each positioning arch15 a, 15 b, 15 c. Hence, although for reasons of clarity not explicitlyshown in FIGS. 16b-g , in the stent design according to the sixteenthembodiment, one leaflet guard arch may be allocated to each positioningarch 15 a, 15 b, 15 c as previously discussed with reference to thetwelfth, thirteenth or fourteenth embodiment.

As already mentioned, the structure of the sixteenth embodiment is quitesimilar to the structure of the previously described fifteenthembodiment. However, the sent design depicted in FIGS. 16b-g differsfrom the fifteenth embodiment particularly with respect to the specificstructure of the respective arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16c″ of the retaining arches 16 a, 16 b, 16 c.

In detail, according to the stent design of the sixteenth embodiment, inthe expanded state of the stent 10, the respective arms 16 a′, 16 a″, 16b′, 16 b″, 16 c′, 16 c″ of the retaining arches 16 a, 16 b, 16 c areformed similar to how a surgical placed tissue valve might beconstructed. Furthermore, the respective arms 16 a′, 16 a″, 16 b′, 16b″, 16 c′, 16 c″ of the retaining arches 16 a, 16 b, 16 c are providedwith a number of additional fastening portions 11 c, each having anumber of additional fastening holes 12 a or eyelets provided forfastening the tissue component(s) of a valvular prosthesis. Theseadditional fastening holes 12 a or eyelets provide for good attachmentpoints of the leaflet and skirt of a heart valve prosthesis attached tothe stent 10.

Hence, according to the stent design of the sixteenth embodiment, in theexpanded state of the stent 10, the respective arms 16 a′, 16 a″, 16 b′,16 b″, 16 c′, 16 c″ of the retaining arches 16 a, 16 b, 16 c have ashape that substantially matches the leaflets of a heart valveprosthesis attached to the stent 10. This specific design of therespective arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of theretaining arches 16 a, 16 b, 16 c is unique for catheter deliveredvalves and has valve durability advantages. The so formed arms 16 a′, 16a″, 16 b′, 16 b″, 16 c′, 16 c″ of the retaining arches 16 a, 16 b, 16 cserve for supporting the skirt and edge of the leaflets of a heart valveprosthesis attached to the stent 10 across the gap behind thepositioning arches 15 a-c. As depicted, for example, in FIGS. 16b-d ,the respective arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of theretaining arches 16 a, 16 b, 16 c follow the shape of the leaflets of avalvular prosthesis (not shown in FIGS. 16b-d ) affixed to the stent 10in its expanded state. Furthermore, the respective arms 16 a′, 16 a″, 16b′, 16 b″, 16 c′, 16 c″ of the retaining arches 16 a, 16 b, 16 c aredesigned to have a minimized unsupported gap from one arm to the otherarm of a retaining arch 16 a, 16 b, 16 c at the location behind thepositioning arches 15 a-c.

In detail and as depicted in the cutting pattern shown in FIG. 16a , therespective arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of theretaining arches 16 a, 16 b, 16 c are provided with a plurality ofbending edges 33. These bending edges 33 divide each arm 16 a′, 16 a″,16 b′, 16 b″, 16 c′, 16 c″ into a plurality of arm segments. The armsegments of a arm 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of theretaining arches 16 a, 16 b, 16 c are interconnected therebyconstituting a retaining arch arm which describes an essentiallystraight line in the not-expanded state of the stent 10. In this regard,reference is also made to the cutting pattern depicted in FIG. 16a whichshows the uncurved configuration of the respective arms 16 a′, 16 a″, 16b′, 16 b″, 16 c′, 16 c″ of the retaining arches 16 a, 16 b, 16 c.

When manufacturing the stent 10, the stent structure and in particularthe structure of the retaining arches 16 a, 16 b, 16 c is programmedsuch that the respective arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″of the retaining arches 16 a, 16 b, 16 c have a curved shape in theexpanded state of the stent 10. The shape of the respective arms 16 a′,16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of the retaining arches 16 a, 16 b, 16c is such defined that the arms follow the shape of the leaflets 102 ofa valvular prosthesis 100 to be affixed to the stent 10 (cf. FIGS. 16fand 16g ).

Hence, the respective arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ ofthe retaining arches 16 a, 16 b, 16 c of the stent 10, onto which thevalvular prosthesis 100 is sewn or sewable, will change their shape whenthe stent 10 expands, wherein the retaining arches 16 a, 16 b, 16 c arecurved in the expanded state of the stent 10, but relatively straightwhen the stent 10 is collapsed.

As can be seen, for example, in FIGS. 16b-d , the curvature of therespective arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of theretaining arches 16 a, 16 b, 16 c is achieved by segmenting the arms 16a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″. In detail, the arms 16 a′, 16 a″,16 b′, 16 b″, 16 c′, 16 c″ are segmented by providing a plurality ofbending edges 33. In the expanded state of the stent 10, two neighboringarm segments are angled relative to each other, wherein the bendingpoint of these two neighboring arm segments is defined by the bendingedge. 33 which is provided in between the both neighboring arm segments.Hence, the greater the number of bending edges 33 provided in an arm 16a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of a retaining arch 16 a, 16 b, 16c, the greater the number of arm segments which may extend in differentdirections in the expanded state of the stent 10. In this respect, theshape of the respective arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ ofthe retaining arches 16 a, 16 b, 16 c can be precisely adapted to theshape of the leaflets of the valvular prosthesis to be affixed to thestent 10.

Reference is made to FIGS. 16f and 16g which show side views of anendoprosthesis 1 for treating a narrowed cardiac valve or a cardiacvalve insufficiency. In the embodiment depicted in FIGS. 16f and 16g ,the stent 10 corresponds to a stent pursuant the sixteenth embodiment ofthe invention for holding a valvular prosthesis 100. The description ofhow the valvular prosthesis 100 is fixed to the stent 10 with respect tothe sixteenth embodiment is also applicable to a stent 10 according tothe other embodiments described herein.

The valvular prosthesis 100 comprises at least one leaflet 102 (see FIG.16f or 16 g) made from a biological or synthetic material. Inparticular, FIGS. 16f and 16g respectively show a side view of theendoprosthesis 1, whereby the cardiac stent 10 is shown in a fullyexpanded state.

To reduce longitudinal displacement of the valvular prosthesis 100affixed to stent 10 relative to the stent 10, even during theperistaltic movement of the heart and the blood vessel in which stent 10is deployed, the stent 10 according to the sixteenth embodiment of theinvention comprises a plurality of fastening portions 11 extending inthe longitudinal direction L of stent 10. In addition, the stent 100according to the sixteenth embodiment is provided with additionalfastening portions 11 b, 11 c. By means of both, the fastening portions11 and the additional fastening portions 11 b, 11 c the tissuecomponent(s) of the valvular prosthesis 100 is affixed to the stent 10.

In detail, the valvular prosthesis 100 is fastened to the stent 10 bymeans of a thread 101 or a thin wire which is guided through fasteningholes 12, 12 a of the fastening portions 11 and the additional fasteningportions 11 b, 11 c, respectively. This allows fixing of the tissuecomponent(s) of the valvular prosthesis 100 to the stent 10 at apredefined position relative to the stent 10.

It can further be seen from the FIG. 16f or FIG. 16g illustration howthe valvular prosthesis 100 can be affixed to the stent 10 by means ofthreads 101. A pericardial valvular prosthesis 100 is used in theembodiment depicted which is sewn to fastening holes 12 f, 12 c providedin the fastening portions 11 c of the retaining arches 16 a, 16 b, 16 con the one hand and in the fastening portions 11 b on the other hand.The valvular prosthesis 100 may be tubular with a substantially circularcross-section. At the lower end 2 of the stent 10, the valvularprosthesis 100 exhibits a bead 105. This bead 105, which is annular inthe plan view of endoprosthesis 1, is formed by turning the lower end ofthe valvular prosthesis 100 inside out by rolling it over on itself anddefines the inflow edge of the endoprosthesis 1.

The annular bead 105 at the lower end of the valvular prosthesis 100 mayprovide anchoring of the peripheral area of the valvular prosthesis 100to the blood vessel in the implanted state of the endoprosthesis 1, evengiven the peristaltic motion, and thus may provide a seal relative thevascular wall. Due to the annular collar 40 provided at the lower endsection 2 of the stent 10, the annular bead 105 at the lower end of thevalvular prosthesis 100 has a round shape adapted to the anatomy in theimplantation side. In this regard, the contact surface between the lowerend section 2 of the endoprosthesis 1 in its expanded and implantedstate and the wall of the blood vessel, into which the endoprosthesis 1is inserted, may be enhanced, thereby improving sealing between theendoprosthesis 1 and the wall of the blood vessel.

The annular bead 105 may achieve a seal of the valvular prosthesis 100at the vascular wall despite the basic triangular structure to the stent10 in a plan view of the expanded endoprosthesis 1. When implanting theendoprosthesis 1 in a native blood vessel any leakage between theperipheral area of the annular bead 105 and the vascular wall may besealed by naturally-occurring accretion, in particular calcification.Accordingly, the bead-shaped area 105 provides a seal, particularly alsoduring the filling phase of the heart cycle (diastole).

The material for the valvular prosthesis 100 and, in particular thematerial for the leaflets 102 of the valvular prosthesis 100 can be madefrom synthetics, animal valves or other animal tissues such aspericardium. The animal tissues can be from a number of types ofanimals. Preferably, the leaflet tissue of the valvular prosthesis 100is from either bovine or porcine pericardium, but other animals can alsobe considered, for example equine, kangaroo, etc.

Animal pericardium is the preferred material for optimum valve designand the ability to collapse into a catheter system having a smalldiameter. Although bovine is preferred, the thickness is generallythicker than porcine and it has been discovered that there may besubstantial swelling of the tissue (35%) during fixation. This swellingmay make bovine more difficult to collapse for small catheter sizedeployment.

As depicted in FIG. 16e , the stent 10 according to the sixteenthembodiment comprises a continuous design of its lower end section 2. Dueto this continuous design, in the implanted and expanded state of thestent 10, via the lower end section 2 of the stent 10 an uniform radialforce is applied to the wall of the blood vessel into which the stent 10is deployed. In this regard, an endoprosthesis 1 constituted by a stent10 according to the sixteenth embodiment and a valvular prosthesis 100affixed to the stent 10 is further secured against migration in theimplanted state of the endoprosthesis 1.

In addition, an improved sealing between the endoprosthesis 1 and thewall of the blood vessel may be achieved when an uniform radial force isapplied from the lower end section 2 of the stent 10 to the wall of theblood vessel.

In order to further improve securing of the position of an implanted andexpanded endoprosthesis 1 and preventing antegrade migration, the stent10 according to the sixteenth embodiment is provided with a flared ortapered section with a radius shape at its lower end section 2. Indetail and as depicted in FIGS. 16b-e , in the expanded state of thestent 10, the lower end section of the annular collar 40 constitutes theflared or tapered section of the stent 10.

The stent 10 depicted in FIGS. 16b-e has at its lower end section 2 aflared or tapered section with a radius shape; however, it is alsoconceivable that the flared or tapered section is not uniformly aroundthe circumference of the stent 10. For example, the stent 10 may have aflare only near the locations of the positioning arches 15 a-c, whereinno flare is provided near the commissure regions, i.e. the regions inbetween the two arms 15 a′, 15 a″, 15 b′, 15 b″, 15 c′, 15 c″ of twoneighboring positioning arches 15 a, 15 b, 15 c.

Although not shown in the drawings, it is particularly preferred for thestent 10 according to any embodiments of the invention that the stent 10has a scalloped inflow edge design at its lower end section 2 when thestent 10 is in its expanded state. Hence, the inflow edge of the stent10 does not lie entirely in a plane perpendicular to the longitudinaldirection L of the stent 10. Rather, the edge of the stent on its inflowside may have a scalloped shape. In addition, the scalloped inflow edgemay also be flared or tapered around its entire circumference or only atselected locations. For example, one embodiment may include a flare atthe inflow edge only near the locations of the positioning arches thattransition to a non-flared straight cylindrical shape in the areabetween two neighboring positioning arches. In particular, the locationof the respective flares and the respective straight cylindrical shapemay be determined by the location of the arms of the respectiveretaining arches to which the tissue component(s) of the valvularprosthesis is attached.

A stent 10 having such a scalloped inflow edge design reduces the lengthof the stent 10 having an inflow edge which lies in a planeperpendicular to the longitudinal direction L of the stent 10 in areasthat have critical structures such as those containing nerve bundles.However, the scallop shape generally follows the native valve annulusand does not compromise the ability of the valve to seal against leakage

The invention is not limited to a stent which is provided with ascalloped inflow edge design. Rather, it is conceivable that the stent10 according to the invention is provided with an inflow edge having anon-continuous flare design or a tapered flare design with an inflowedge that lies in a plane perpendicular to the longitudinal direction Lof the stent 10 or a design which is provided with flaresnon-continuously distributed around the inflow edge or with flareshaving a tapered configuration for inflow edge of a stent 10 that doesnot lie entirely in a plane perpendicular to the longitudinal directionL of the stent 10.

A stent 10 according to a seventeenth embodiment of the invention isshown in FIGS. 17b to 17e . In particular, FIG. 17b is a firstperspective side view of a cardiac valve stent according to theseventeenth embodiment of the invention, whereby the cardiac valve stent10 is shown in its expanded state. Second and third side views of thecardiac valve stent 10 in its expanded state are shown in FIGS. 17c and17 d.

On the other hand, FIG. 17e shows a plan view of the upper end of thecardiac valve stent 10 according to the seventeenth embodiment of theinvention in its expanded state.

A flat roll-out view of a stent 10 according to the seventeenthembodiment is shown in FIG. 17 a.

The seventeenth embodiment of the stent 10 is similar in structure andfunction with respect to the sixteenth embodiment. However, the sentdesign depicted in FIGS. 16b-e differs from the sixteenth embodimentparticularly with respect to the specific structure of the annularcollar 40. In detail, the seventeenth embodiment is provided with anannular collar 40 which is shortened in its length by having only onerow of cells instead of two in the annular collar.

The above described embodiments of the inventive stent have a specificstructure that can provide some flexing during diastole to relieve andbetter distribute leaflet stresses in order to avoid high stressconcentrations at the attachment points at which the valvular prosthesis100 is connected to the stent 10. For offering flexibility to theleaflets 102 of a heart valve prosthesis 100 attached to the stent 10and for enhancing the durability of the prosthesis 100 affixed to thestent 10, the stent 10 preferably has not a continuous cage around thecircumference at the top of the new valve commissures, i.e. thecommissures of a valvular prosthesis 100 affixed to the stent 10. Inthis regard, there is some inherent flexibility of the stentcommissures.

In particular, the stents 10 described herein, which are not providedwith an upper collar 40′ at the upper end section 3 of the stent 10,offer valve commissure flexibility advantages over other cage valvedesigns. Surgical biological prosthetic valves are designed with stentsthat provide some flexibility at the upper end section of the valvecommissures to reduce stress concentrations in the valve leaflets thatenhances the longevity (i.e. valve durability) of the prosthesis and toimprove leaflet coaptation.

It is preferred that the stent diameter at the base, i.e. the diameterat the lower end section 2 of the stent 10, should be able toaccommodate a range of annulus diameters around the target diameter.Within this range the forces applied due to the stiffness should beadequate to prevent migration, but not too great to cause annularrupture. At the top of the commissures, it is desirable that the stentnot vary in diameter significantly to minimize the impact to the valvecoaptation or opening performance even when the annulus diameter is notexactly at the target diameter.

In addition, the overall stent height should be minimized to shorten thedelivery section of the catheter. This is important because the portionof the delivery catheter system containing the endoprosthesis 1 isgenerally stiff relative to the rest of the catheter system. In case ofa transfemoral approach, it is an advantage to have greater flexibilityin the catheter system to follow the curves of the patient anatomy (e.g.the ascending aorta).

As already discussed in connection with the sixteenth embodiment, a morecontinuous base design may provide uniform radial force to secure thevalve against migration. Uniform radial force may also minimize leakagein the implanted stage. Preferably, the base of the stent 10 is flaredwith a radius shape or a slight taper to a larger diameter as shown, forexample, in FIG. 17b . In this respect, this stent design may furtherimprove securing the valve position and preventing antegrade migration.

As depicted in FIG. 17e , the stent 10 according to the seventeenthembodiment comprises a continuous design of its lower end section 2. Dueto this continuous design, in the implanted and expanded state of thestent 10, via the lower end section 2 of the stent 10 an uniform radialforce is applied to the wall of the blood vessel into which the stent 10is deployed. Furthermore, the stent 10 depicted in FIGS. 17b-e has atits lower end section 2 a flared or tapered section with a radius shape;however, it is also conceivable that the flared or tapered section isnot uniformly around the circumference of the stent 10.

If the implanted and expanded stent together with a valvular prosthesisaffixed thereto cannot extend too far below the annulus of the heartthere may be the risk that the implanted endoprosthesis consisting ofthe stent one the one hand and the valvular prosthesis on the other handcontacts the nerve bundles and heart block. The nerve bundles may enterat a location approximately 6 to 10 mm below the annulus of the heart.

In this regard, it may be preferred to reduce the total height of thestent and thus the total height of the endoprosthesis to be implantedinto the body of the patient. As in the seventeenth embodiment depictedin FIGS. 17a-e , this can be achieved by having one row of cells in theannular collar 40 instead of two rows of cells as, for example, in thestent design of the fourteenth embodiment (cf. 14 a-b).

On the other hand, also a scalloped inflow edge design is conceivable.Hence, the stent 10 may have a scalloped inflow edge design at its lowerend section 2 when the stent 10 is in its expanded state. With such adesign, the inflow edge of the stent 10 does not lie in a planeperpendicular to the longitudinal direction L of the stent 10. Rather,the edge of the stent on its inflow side may have a scalloped shape withflares near the locations of the positioning arches and indentations inthe area between two neighboring positioning arches. In particular, theshape and location of the respective flares and the respectiveindentations may be determined by the arms of the respective retainingarches to which the tissue component(s) of the valvular prosthesis isattached.

The stent 10 is preferably made from a shape memory material. The stateof stent 10 shown in FIG. 1a or FIG. 2a , in which the stent 10 is inits first shape and thus in its collapsed state, is the so-called“temporary” shape of the stent structure made from a shape memorymaterial. When an external stimulus acts on the stent structureaccording to FIG. 1a or FIG. 2a , the shape memory effect is activated.Thus, the predefined permanent shape saved during the manufacture of thestent 10 as pursuant, for example, FIG. 1b or FIG. 2b , is restoredprovided that no encapsulating forces, i.e. radially inward actingforces, act on the stent to keep the stent in its collapsed state.

Said external stimulus is preferably a specifiable switching temperaturewhereby, to activate the shape memory effect and thus regenerate thesaved permanent shape of the stent 10, the stent material is warmed to ahigher temperature than the switching temperature. By selecting asuitable chemical composition of the material used for stent 10, aspecific switching temperature can be predefined. In the preferredembodiment of the solution described herein, the switching temperatureranges from between about 20° C. and the body temperature of thepatient.

The surface of the stent 10 should be smooth and edges should be roundedto maximize fatigue, biocompatibility and minimize damage to attachedtissue and sutures or damage to native tissue. Hence, it is preferredthat the surface of the stent 10 is polished, for exampleelectropolished. Polishing of the stent surface can be performed beforeor after the programming process during which the shape of the desired(expanded) stent structure is fixed.

When implanting the stent 10, it is conceivable for the stent 10 to becooled during the insertion procedure. Once the stent 10 has been guidedto its desired site of implantation, i.e. to the native cardiac valve H(cf. FIG. 18a ), preferably using a suitable insertion catheter system,the cooling can be stopped. The stent 10 is then allowed to warm up tothe patient's body temperature (37° C.) and the shape memory effect ofthe stent material is thus activated. Due to the self-expanding propertyof stent 10 having been triggered, radial forces are generated which acton the individual components of the stent, in particular on thepositioning arches 15 a, 15 b, 15 c, the retaining arches 16 a, 16 b, 16c and the auxiliary arches 18 a, 18 b, 18 c of the stent 10.

The stent 10 described herein, as well as the insertion catheter systemused to implant the stent, are preferably configured so that the stent10 with the valvular prosthesis 100 affixed thereto can be introducedtransarterialiy into the body of the patient. In one example, the stent10 is accommodated in the tip of the catheter of the insertion cathetersystem, the catheter tip being introduced into the body via, forexample, puncture of the A. femoris communis (inguinal artery). Asuitable catheter system is described in WO2006/076890 andPCT/EP2008/003803, the details of which are incorporated herein byreference.

Alternatively, the stent 10 according to certain embodiments of theinvention is also suited for transapical implantation, in which—comingfrom the apex of the heart—the catheter tip of the insertion cathetersystem is advanced to the aortic valve through, for example, the leftventricle. With a catheter tip modified accordingly, an analogousimplantation of the stent 10 with the valvular prosthesis 100 is thuspossible. A suitable catheter system is described in PCT/EP2008/003803,the details of which are incorporated herein by reference

Regardless of whether the stent 10 is delivered to the site ofimplantation via a transarterial or transapical approach, the tip of thecatheter of the insertion catheter system is preferably advanced to theimplantation site using angiographic (angiography) and echocardiographic(ultrasound) control. The actual implantation of stent 10 with theattached valvular prosthesis 100 then follows.

FIGS. 18a to 18c schematically show the process sequence to illustratetransarterial implantation of an endoprosthesis 1 comprising a stent 10in accordance with certain embodiments of the invention. As shown, theimplantation of the stent 10 with the valvular prosthesis 100 attachedthereto ensues such that the individual components of the stent 10accommodated in a delivery portion of a catheter system are successivelyreleased by appropriately manipulating the delivery portion of aninsertion catheter system.

The catheter system used to implant the stent 10 described herein isideally configured such that a liquid cooling agent can be fed through ahollow interior of the catheter system to the delivery portion of thecatheter system. The liquid cooling agent, for example in the form of asaline solution, maintains the stent 10 accommodated in the deliveryportion of the catheter system at a temperature below the switchingtemperature while the proximal side K of the delivery portion of thecatheter system is being advanced to the site of implantation. This isof particular advantage when a shape memory material is provided as thematerial of the stent 10. This is because the stent 10 transforms from atemporary shape into a permanent shape upon the influence of an externalstimulus. The temporary shape is the first shape of stent 10 (incollapsed state, when the stent 10 is accommodated in the deliveryportion of the catheter system) and the “permanent shape” is the secondshape of stent 10 (the expanded state of the stent 10).

It is to be noted that the “permanent shape” of the expanded stent 10conforms to the native shape of its environment. This allows forvariations in the shape of the environment at the site of implantationwhich will vary from patient to patient. This property of stent 10,related to the “permanent shape” of the expanded stent 10 automaticallyadapting completely to the native shape of its environment, will thusalways ensure that the valvular prosthesis 100 is optimally implanted.

The difference between the fully expanded permanent shape of the stent10 and the constrained shape of the stent 10 in its implanted stagedepends from the environment at the side of implantation and determinesthe radial pressures applied by the stent 10 to the vessel wall forpreventing migration and for assuring good sealing. The fully expandedshape of the stent 10 is designed to provide the appropriate radialpressures for the target patient anatomy size.

Because a shape memory material such as Nitinol, i.e. an equiatomicalloy of nickel and titanium, can be used for the stent 10 describedherein, a particularly gentle implantation procedure is achievable whenimplanting the stent 10 with the valvular prosthesis 100 affixedthereto. Nitinol as material for the stent 10 is preferred because ofits good biocompatibility.

The stent 10 accommodated in the delivery portion of the catheter systemcan be cooled by flushing the insertion catheter system with a suitablecooling agent while the delivery portion of the catheter system is beingadvanced to keep the temperature of the stent material below thecritical transition temperature. Once the delivery portion of thecatheter system with the cooled stent 10 has been advanced to the siteof implantation, cooling of the stent 10 should be stopped, as aconsequence of which the stent 10 warms up to the body temperature (37°C.) of the patient and the shape memory effect of the stent material isthus activated.

Once the self-expanding property of the individual components of stent10 have been activated, radial forces are generated which act on theindividual components of stent 10, in particular on the positioningarches 15 a, 15 b, 15 c, the retaining arches 16 a, 16 b, 16 c, theleaflet guard arches 50 a, 50 b, 50 c and the auxiliary arches 18 a, 18b, 18 c of stent 10. Since the respective components of stent 10 arestill situated in the delivery portion of the catheter system, theradial forces developing upon the critical switching temperature beingexceeded and acting on the individual components of the stent 10 arestill compensated by the wall of the delivery portion of the cathetersystem, so that—despite the activation of the shape memory effect—thestent 10 is forcibly kept in its first (collapsed) shape.

Upon the subsequent manipulation of the delivery portion of the cathetersystem—by the appropriate incremental release of the stent 10—theindividual components of stent 10, are then discharged from the deliveryportion of the catheter system.

For example, as FIG. 18a shows, the positioning arches 15 a, 15 b, 15 cof stent 10 spread out radially due to the acting radial forces. Theexpanded positioning arches 15 a, 15 b, 15 c can then be positioned intothe pockets T of the native cardiac valve H.

Thereafter—as depicted in FIG. 18b —the remaining components of stent 10are sequentially released from the delivery portion of the cathetersystem. The released remaining components of stent 10, in particular theauxiliary arches 18 a, 18 b, 18 c and the retaining arches 16 a, 16 b,16 c with the valvular prosthesis 100, then spread out radially and thevalvular prosthesis 100 attached to the fastening portions 11 unfoldslike an umbrella.

The radial forces acting on both the retaining arches 16 a, 16 b, 16 cand the auxiliary, arches 18 a, 18 b, 18 c of the stent 10 as well asthe radial forces acting on the upper end region 3 of stent 10, resultin the stent 10 being pressed radially against the vascular wall (cf.FIG. 18c ). This effects a secure anchoring of stent 10 with theexpanded valvular prosthesis 100 at the site of implantation on the onehand and, on the other, a reliable seal of the valvular prosthesis 100at the lower end 2 of stent 10.

The delivery portion of the insertion catheter system is thenmanipulated further to release the eyelets 24 of the stent 10, therebyallowing the upper end region 3 of the stent 10 to expand. In so doing,the leaflets of the native cardiac valve H are clamped betweenrespective positioning and retaining arches and the valvular prosthesis100 disposed on the lower end 2 of stent 10 can spread open.

After the successful implantation of the stent 10 and valvularprosthesis 100, the catheter is then removed from the body of thepatient.

The stent 10 is not limited to being made from shape memory materialwhich self-expands from its first (collapsed) shape into its second(expanded) shape in response to an external stimulus. Rather, it is alsocategorically conceivable for the stent 10 to be expanded using aconventional balloon system.

It will be appreciated that the solution described herein is also notlimited to the specific embodiments as described with reference to theattached drawings. Rather, the invention encompasses combinations of theindividual features exemplified in the embodiments described.

In particular, the stent 10 may not be provided with radial arches 32a-c. Rather, the base configuration of the stent 10 may only comprise aplurality of positioning arches 15 a-c and a plurality of retainingarches 16 a, 16 b, 16 c.

A eighteenth embodiment of the stent 10 according to the presentinvention is described in the following with reference to FIGS. 19a-b .In detail, FIG. 19a shows a first perspective side view of a cardiacvalve stent capable of supporting and anchoring an endoprosthesisaccording to the eighteenth embodiment of the invention, whereby thecardiac valve stent is shown in its expanded state, and FIG. 19b shows asecond perspective side view of a cardiac valve stent capable ofsupporting and anchoring an endoprosthesis according to the eighteenthembodiment of the invention, whereby the cardiac valve stent is shown inits expanded state.

Hence, the stent 10 according to the eighteenth embodiment comprises aplurality of positioning arches 15 a, 15 b, 15 c configured to bepositioned within a plurality of pockets T of the patient's native heartvalve H and positioned on a first side of a plurality of native heartvalve leaflets, and a plurality of retaining arches 16 a, 16 b, 16 cconfigured to be positioned on a second side of the plurality of nativeheart valve leaflets opposite the first side, wherein furthermore aplurality of leaflet guard arches 50 a, 50 b, 50 c are provided, eachinterspaced between the two arms 15 a′, 15 a″, 15 b′, 15 b″, 15 c′, 15c″ of one of the plurality of positioning arches 15 a, 15 b, 15 c. Inaddition, the respective arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″of the retaining arches 16 a, 16 b, 16 c are preferably provided with aplurality of bending edges 33 in order to divide each arm 16 a′, 16 a″,16 b′, 16 b″, 16 c′, 16 c″ into a plurality of arm segments, wherein thestructure of the stent 10 is programmed such that the respective arms 16a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of the retaining arches 16 a, 16b, 16 c have a curved shape at least in the expanded state of the stent10. In particular, the shape of the respective arms 16 a′, 16 a″, 16 b′,16 b″, 16 c′, 16 c″ of the retaining arches 16 a, 16 b, 16 c shall besuch defined that the arms follow the shape of the leaflets 102 of avalvular prosthesis 100 to be affixed to the stent 10 (cf. FIGS. 16f and16g ).

In addition, the stent 10 according to the eighteenth embodiment mayfurther include at least one auxiliary arch 18 a, 18 b, 18 c interspacedbetween two adjacent retaining arches 16 a, 16 b, 16 c, wherein the atleast one auxiliary arch 18 a, 18 b, 18 c includes a first arm 18 a′, 18b′, 18 c′ connected at a first end thereof to a first retaining arch 16a, 16 b, 16 c and a second arm 18 a″, 18 b″, 18 c″ connected at a firstend thereof to a second retaining arch 16 a, 16 b, 16 c, and wherein thefirst and second arms 18 a′, 18 a″, 18 b′, 18 b″, 18 c′, 18 c″ of the atleast one auxiliary arch 18 a, 18 b, 18 c each include respective secondends connected to one another at a joint that includes at least onefastening hole configured to receive a suture.

In addition or instead of the at least one auxiliary arch 18 a, 18 b, 18c, the stent according to the eighteenth embodiment of the invention mayfurther comprise at least one radial arch 32 a, 32 b, 32 c substantiallycircumferentially aligned with at least one of the plurality ofpositioning arches 15 a, 15 b, 15 c.

Furthermore, the stent 10 according to the eighteenth embodiment of theinvention may also be provided with a plurality of extra arches 60 a, 60b, 60 c, each of said plurality of extra arches 60 a, 60 b, 60 c beinginterspaced between a first retaining arch 16 a, 16 b, 16 c and anadjacent second retaining arch 16 a, 16 b, 16 c.

Also, at least one annular collar 40, 40′ may be provided at the lowerend section 2 and/or at the upper end section 3 of the stent 10according to the eighteenth embodiment of the invention.

Moreover, with respect to fixing the upper area 3 of stent 10 to thewall of the blood vessel into which the stent 10 is deployed, it wouldbe conceivable for the stent 10 to comprise barb members arranged, forexample, on the eyelets 24, the tips of the barbs pointing toward thelower end 2 of stent 10.

In addition, a liner or sheath, typically a fabric, polymeric orpericardial sheet, membrane, or the like, may be provided over at leasta portion of the exterior of the stent 10 to cover all or most of thesurface of the outside of the stent 10, extending from a location nearthe lower end section of the stent to a location near the upper endsection of the stent. The liner may be attached to the stent 10 at atleast one end, as well as at a plurality of locations between said endsthereby forming an exterior coverage. Such exterior coverage provides acircumferential seal against the inner wall of the blood vessel lumen inorder to inhibit leakage of blood flow between the stent 10 and theluminal wall thereby and to prevent a blood flow bypassing theendoprosthesis 1.

For example, the liner may be stitched or otherwise secured to the stent10 along a plurality of circumferentially spaced-apart axial lines. Suchattachment permits the liner to fold along a plurality of axial foldlines when the stent 10 is radially compressed. The liner will furtherbe able to open and conform to the luminal wall of the tubular frame asthe frame expands. Alternatively, the liner may heat welded, orultrasonically welded to the stent 10. In an exemplary embodiment wherethe stent 10 is provided with a plurality of independent fasteningportions 11, 11 a, the liner may be secured at these fastening portions11, 11 a. In a second exemplary embodiment where a plurality ofindependent arches (positioning arches 15 a, 15 b, 15 c, retainingarches 16 a, 16 b, 16 c, auxiliary arches 18 a, 18 b, 18 c and/orfastening arches 19, 19 a, 19 b, 19 c) are provided, the liner issecured to these arches preferably along axial lines. The liner willpreferably be circumferentially sealed against the stent 10 at at leastone end.

By covering at least a part of the outside surface of the stent 10 withthe liner or sheath, thrombogenicity of the endoprosthesis 1 resultingfrom exposed stent elements is greatly reduced or eliminated. Suchreduction of thrombogenicity is achieved while maintaining the benefitsof having a stent structure which is used for spreading up a valvularprosthesis 100 and for anchoring the valvular prosthesis 100 in place.

As already mentioned, the stent 10 can be compressed from a relaxed,large diameter configuration to a small diameter configuration tofacilitate introduction. It is necessary, of course, that the outerliner remain attached to the stent 10 both in its radially compressedconfiguration and in its expanded, relaxed configuration.

The liner is composed of pericardial material or conventional biologicalgraft materials, such as polyesters, polytetrafluoroethylenes (PTFE's),polyurethanes, and the like, usually being in the form of woven fabrics,non-woven fabrics, polymeric sheets, membranes, and the like. Apresently preferred fabric liner material is a plain woven polyester,such as Dacron® yarn (Dupont, Wilmington, Del.).

A nineteenth embodiment of the stent 10 according to the presentinvention is described in the following with reference to FIGS. 20a to20 d.

In detail, FIG. 20a shows a flat roll-out view of a cardiac valve stent10 pursuant the nineteenth embodiment of the invention, whereby thestent 10 is in its non-expanded state. This flat roll-out viewcorresponds to a two-dimensional projection of a cutting pattern whichcan be used in the manufacture of the stent 10 pursuant the nineteenthembodiment of the invention. This enables a one-piece stent 10 to be cutfrom a portion of tube, in particular a metal tube. It is evident that,on the one hand, the inventive stent 10 dispenses with fixed-body jointsor other similar connective devices between the individual components ofstent 10 (positioning arch, retaining arch, auxiliary arch). On theother hand, a stent 10 is provided which exhibits, with minimumlongitudinal extension, the functionality of positionability as providedby the positioning arches 15 a, 15 b, 15 c on the one hand and, on theother hand, the functionality of the defined fastening of a valvularprosthesis, as provided by the fastening portions 11 configured in therespective arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of theretaining arch 16 a, 16 b, 16 c. Moreover, the defined fastening of avalvular prosthesis is achieved by additional fastening means whichcomprise a several number of notches 12 e uniformly distributed aroundthe lower end section of an annular collar 40 which is arranged at thelower end section of the stent body.

FIG. 20b shows a first perspective side view of a cardiac valve stent 10capable of supporting and anchoring an endoprosthesis according to thenineteenth embodiment of the invention, whereby the cardiac valve stent10 is shown in its expanded state, and FIG. 20c shows a secondperspective side view of a cardiac valve stent capable of supporting andanchoring an endoprosthesis according to the nineteenth embodiment ofthe invention, whereby the cardiac valve stent is also shown in itsexpanded state.

FIG. 20d shows a flat roll-out view of a cardiac valve stent 10according to the nineteenth embodiment of the invention. Contrary to theflat roll-out view depicted in FIG. 20a , however, the flat roll-outview according to FIG. 20d shows the cardiac valve stent 10 is in itsexpanded state.

Thus, it appears that the stent 10 according to the nineteenthembodiment comprises a plurality of positioning arches 15 a, 15 b, 15 cand a plurality of retaining arches 16 a, 16 b, 16 c. Each of theplurality of positioning arches 15 a, 15 b, 15 c is configured to bepositioned within a plurality of pockets T of the patient's native heartvalve H and positioned on a first side of a plurality of native heartvalve leaflets (see FIGS. 18a to 18c ). On the other hand, each of theplurality of retaining arches 16 a, 16 b, 16 c is configured to bepositioned on a second side of the plurality of native heart valveleaflets opposite the first side (see also FIGS. 18a-c ).

Furthermore, a plurality of leaflet guard arches 50 a, 50 b, 50 c areprovided, each interspaced between the two arms 15 a′, 15 a″, 15 b′, 15b″, 15 c′, 15 c″ of one of the plurality of positioning arches 15 a, 15b, 15 c. In addition, the respective arms 16 a′, 16 a″, 16 b′, 16 b″, 16c′, 16 c″ of the retaining arches 16 a, 16 b, 16 c are preferablyprovided with a plurality of bending edges 33 in order to divide eacharm 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ into a plurality of armsegments, wherein the structure of the stent 10 is programmed such thatthe respective arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of theretaining arches 16 a, 16 b, 16 c have a curved shape at least in theexpanded state of the stent 10. In particular, the shape of therespective arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of theretaining arches 16 a, 16 b, 16 c shall be such defined that the armsfollow the shape of the leaflets 102 of a valvular prosthesis 100 to beaffixed to the stent 10.

In detail and as depicted in the flat roll-out view shown in FIG. 20a ,the respective arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of theretaining arches 16 a, 16 b, 16 c are provided with a plurality ofbending edges 33. These bending edges 33 may be uniformly distributedalong the length of each retaining arch arm 16 a′, 16 a″, 16 b′, 16 b″,16 c′, 16 c″ thereby dividing each arm 16 a′, 16 a″, 16 b′, 16 b″, 16c′, 16 c″ into a plurality of arm segments. The arm segments of acorresponding retaining arch arm 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16c″ are interconnected thereby constituting a retaining arch arm whichdescribes an essentially straight line in the not-expanded state of thestent 10. In this regard, reference is made to the flat roll-out viewdepicted in FIG. 20a which shows the uncurved configuration of therespective arms 16 a′, 16 a″, 16 b′, 16 b″, 16 e, 16 c″ of the retainingarches 16 a, 16 b, 16 c.

When manufacturing the stent 10, the stent structure and in particularthe structure of the retaining arches 16 a, 16 b, 16 c is programmedsuch that the respective retaining arch arms 16 a′, 16 a″, 16 b′, 16 b″,16 c′, 16 c″ have a curved shape in the expanded state of the stent 10.The shape of the respective retaining arch arms 16 a′, 16 a″, 16 b′, 16b″, 16 c′, 16 c″ is such defined that the arms follow the shape of theleaflets of a valvular prosthesis 100 to be affixed to the stent 10 (cf.FIG. 20d ).

Hence, the respective retaining arch arms 16 a′, 16 a″, 16 b′, 16 b″, 16c′, 16 c″, onto which the valvular prosthesis 100 is sewn or sewable,will change their shape when the stent 10 expands, wherein the retainingarches 16 a, 16 b, 16 c are curved in the expanded state of the stent10, but relatively straight when the stent 10 is collapsed.

As can be seen, for example, in FIG. 20d , the curvature of therespective retaining arch arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″is achieved by segmenting the arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16c″. In detail, the arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ aresegmented by providing a plurality of bending edges 33. In the expandedstate of the stent 10, two neighboring arm segments are angled relativeto each other, wherein the bending point of these two neighboring armsegments is defined by the bending edge 33 which is provided in betweenthe both neighboring arm segments. Hence, the greater the number ofbending edges 33 provided in an arm 16 a′, 16 a″, 16 b′, 16 b″, 16 c′,16 c″ of a retaining arch 16 a, 16 b, 16 c, the greater the number ofarm segments which may extend in different directions in the expandedstate of the stent 10. In this respect, the shape of the respectiveretaining arch arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ can beprecisely adapted to the shape of the leaflets of the valvularprosthesis to be affixed to the stent 10.

According to the stent design of the nineteenth embodiment, therespective arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of theretaining arches 16 a, 16 b, 16 c are not provided with fastening holes12 a, as it is the case, for example, in the eighteenth or seventeenthembodiment. Rather, in the nineteenth embodiment, the bending edges 33provided in the retaining arch arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′,16 c″ are not only used for defining a bending point of two neighboringarm segments, but also as fastening notches which can be used for fixinga heart valve prosthesis to the stent 10.

A comparison with, for example, the flat roll-out view pursuant to FIG.17a (seventeenth embodiment) illustrates directly that the respectiveretaining arch arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of thestent design according to the nineteenth embodiment is at least partlymuch more thinner compared with the respective retaining arch arms ofthe seventeenth embodiment which are provided with fastening portionshaving fastening holes 12 a. By reducing the thickness of the retainingarch arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″, the bendability ofthe arms is increased which allows a more precise adaptation of theshape of the respective retaining arch arms 16 a′, 16 a″, 16 b′, 16 b″,16 c′, 16 c″ to the shape of the leaflets of the valvular prosthesis tobe affixed to the stent 10.

Moreover, by using the bending edges 33 provided in the retaining archarms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ as fastening notches forfixing a heart valve prosthesis to the stent 10, a greater number ofattachment points compared with the number of fastening holes 12 a canbe generated. In this regard, high stress concentrations at each singleattachment point can be effectively avoided.

In addition, in the nineteenth embodiment, the attachment points(bending edges 33) to be used for fixing a heart valve prosthesis to theretaining arch arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″ of thestent 10 are more uniformly distributed along the respective retainingarch arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′, 16 c″, thereby providing amore uniform fixation of a heart valve prosthesis to the stent. Hence,the risk of an axial displacement of the heart valve prosthesis relativeto the stent may be further reduced. Each individual bending edge 30provided in the respective retaining arch arms 16 a′, 16 a″, 16 b′, 16b″, 16 c′, 16 c″ thereby serves to guide a thread or thin wire withwhich the tissue component(s) of the valvular prosthesis is affixed orsewn to the corresponding retaining arch arm 16 a′, 16 a″, 16 b′, 16 b″,16 c′, 16 c″ of the stent 10. In detail, the means (thread or thin wire)provided for fastening the tissue component(s) of the valvularprosthesis to the respective retaining arch arms 16 a′, 16 a″, 16 b′, 16b″, 16 c′, 16 c″ is guided by way of the bending edge 33 acting asfastening notch so that a longitudinal displacement of the valvularprosthesis relative to the stent 10 is substantially minimized. Thisalso allows exact positioning of the valvular prosthesis relative thestent 10.

In addition, the stent 10 according to the nineteenth embodiment mayfurther include at least one auxiliary arch 18 a, 18 b, 18 c interspacedbetween two adjacent retaining arches 16 a, 16 b, 16 c, wherein the atleast one auxiliary arch 18 a, 18 b, 18 c includes a first arm 18 a′, 18b′, 18 c′ connected at a first end thereof to a first retaining arch 16a, 16 b, 16 c and a second arm 18 a″, 18 b″, 18 c″ connected at a firstend thereof to a second retaining arch 16 a, 16 b, 16 c, and wherein thefirst and second arms 18 a′, 18 a″, 18 b′, 18 b″, 18 c′, 18 c″ of the atleast one auxiliary arch 18 a, 18 b, 18 c each include respective secondends connected to an annular collar 40 which is arranged at the lowerend section of the stent body. As in the previously described stentdesign (14^(th) to 18^(th) embodiment), this at least one collar 40serves as an additional anchoring measure for a stent cut from a portionof a tube by using the cutting pattern depicted in FIG. 20 a.

In detail, the respective first and second arms 18 a′, 18 a″, 18 b′, 18b″, 18 c′, 18 c″ of the at least one auxiliary arch 18 a, 18 b, 18 c arepart of a strut or web structure which is provided between the first andsecond arms 18 a′, 18 a″, 18 b′, 18 b″, 18 c′, 18 c″ of two adjacentauxiliary arches 18 a, 18 b, 18 c in order to support a valvularprosthesis 100 to be affixed to the stent 10 (see, for example, FIGS.16f and 16g ). As can be seen, for example, from FIG. 20d the strut orweb structure may be composed by a plurality of struts or strut-likemembers which are interconnected such as to form a reinforcementstructure. Each strut or strut-like element of the reinforcementstructure serves as reinforcement member in order to increase thestrength or resistance to deformation of the area between the first andsecond arms 18 a′, 18 a″, 18 b′, 18 b″, 18 c′, 18 c″ of two adjacentauxiliary arches 18 a, 18 b, 18 c. The reinforcement structure therebyprovides mechanical reinforcement to the stent 10. Moreover, thereinforcement members of the reinforcement structure between the firstand second arms 18 a′, 18 a″, 18 b′, 18 b″, 18 c′, 18 c″ of two adjacentauxiliary arches 18 a, 18 b, 18 c provides for an additional support ofthe commissures of a heart valve prosthesis attached to the stent 10.

The terms “strength” or “resistance to deformation” as used herein maybe used to denote any of a number of different properties associatedwith the reinforcement members. For example, the terms may be used torefer to properties of the material from which the reinforcement membersare made, such as the yield strength, the modulus of elasticity, themodulus of rigidity, or the elongation percentage. Similarly, the termsmay be used to refer to the hardness of the reinforcement members.Hardness may be characterized as the “durometer” of the material, inreference to the apparatus used to measure the hardness of the material.The terms may also be used to denote geometric characteristics of thereinforcement members, such as the thickness of the reinforcementmembers. The terms “strength” or “resistance to deformation” may also beused to characterize any combination of the above properties as well asadditional properties and/or characteristics.

The strength or resistance to deformation of the area between the firstand second arms 18 a′, 18 a″, 18 b′, 18 b″, 18 c′, 18 c″ of two adjacentauxiliary arches 18 a, 18 b, 18 c can be increased in any number ofways. As can be seen from FIG. 20d , the strength or resistance todeformation of the area between the first and second arms 18 a′, 18 a″,18 b′, 18 b″, 18 c′, 18 c″ of two adjacent auxiliary arches 18 a, 18 b,18 c can be increased, for example, by providing a reinforcementstructure formed by at least one, and preferably by a plurality ofreinforcement elements (e.g. struts or strut-like members) which areinterconnected to each other.

It is also conceivable that a reinforcement web is provided in order toincrease the strength or resistance to deformation of the area betweenthe first and second arms 18 a′, 18 a″, 18 b′, 18 b″, 18 c′, 18 c″ oftwo adjacent auxiliary arches 18 a, 18 b, 18 c. This reinforcement webmay also be composed by a plurality of reinforcement elements (e.g.struts or strut-like members) which are interconnected to each otherthereby forming a rhomboidal pattern.

The strength or resistance to deformation of the area between the firstand second arms 18 a′, 18 a″, 18 b′, 18 b″, 18 c′, 18 c″ of two adjacentauxiliary arches 18 a, 18 b, 18 c can be increased, for example, byincreasing the thickness of the reinforcement members, by eliminatingstress concentration risers in the design of the stent 10, or bychanging other aspects of the geometry of the reinforcement members. Thestrength can also be increased by changing the material properties ofthe stent 10 and/or the reinforcement members. For example, thereinforcement members can be made from a number of different materials,preferably shape memory materials, each having a different level ofhardness. In this regard, it is conceivable to vary the stoichiometriccomposition of the material used for forming the stent and thereinforcement members such as to adapt the material properties of thestent 10 and/or the reinforcement members to the specific needs of eachstent application. It is also conceivable to use different materials,for example nitinol and a shape-memory polymer, for forming the stentand the reinforcement members. In this manner, the selection of thereinforcement members can be tailored to the specific needs of eachstent application. For example, in regions where a high external forceis expected, reinforcement members having a high hardness may bepreferred. The strength may also be increased by combining materialproperties with geometric changes.

As can be seen from FIG. 20d , the stent 10 according to the nineteenthembodiment is provided with a reinforcement structure which isconstituted by a plurality of lattice cells 70 formed by a plurality ofstruts in the area between the arms 16 a′, 16 a″, 16 b′, 16 b″, 16 c′,16 c″ of two neighbouring (adjacent) retaining arches 16 a, 16 b, 16 c,thereby providing for an additional support of the commissures of aheart valve prosthesis attached to the stent 10.

In addition, this structure of the lattice cells 70 formed by aplurality of struts in the area between the adjacent arms of twoneighbouring retaining arches 16 a, 16 b, 16 c may provide uniform stentstructure which may minimize blood leakage in the implanted stage of thestent 10 having a heart valve prosthesis attached thereto.

The upper end sections of the respective struts which are forming thestructure of the lattice cells 70 are connected to the respective armsof the retaining arches 16 a, 16 b, 16 c. Preferably, the upper endsections of the struts comprise a widened diameter in order tostrengthen the connection between the upper end sections of the strutsand the arms of the retaining arches 16 a, 16 b, 16 c.

The already mentioned annular collar 40, which is provided at the lowerend section of the stent body, is connected with the stent body via theretaining arches 16 a, 16 b, 16 c on the one hand and the second ends ofthe respective arms 18 a′, 18 a″, 18 b′, 18 b″, 18 c′, 18 c″ of the atleast one auxiliary arch 18 a, 18 b, 18 c on the other hand, whereinthese arms 18 a′, 18 a″, 18 b′, 18 b″, 18 c′, 18 c″ of the at least oneauxiliary arch 18 a, 18 b, 18 c are part of the structure of the latticecells 70. In particular, the stent 10 according to the nineteenthembodiment of the invention is provided with an annular collar 40 whichis shortened in its length by having only a single row of cells.

As can be seen from the flat roll-out view pursuant to FIG. 20a , theannular collar 40 at the lower end section of the stent body exhibits aplurality of supporting webs 41 which run parallel to the longitudinalaxis L of the stent 10 in the non-expanded state of the stent 10 and areinter-connected by transversal webs 42. As can be seen from thetwo-dimensional roll-out view pursuant to FIG. 20c , however, in theexpanded state of the stent 10, the supporting webs 41 and thetransversal webs 42 forms a rhomboidal or serpentine-like annular collar40 which abuts against the vascular wall in the implanted state of thestent 10.

In order to further improve securing of the position of an implanted andexpanded endoprosthesis 1 and preventing antegrade migration, the stent10 according to the nineteenth embodiment is provided with a flared ortapered section with a radius shape at its lower end section 2. Indetail and as depicted in FIGS. 20b and 20c , in the expanded state ofthe stent 10, the lower end section of the annular collar 40 constitutesthe flared or tapered section of the stent 10.

The stent 10 depicted in FIGS. 20b and 20 c has at its lower end section2 a flared or tapered section with a radius shape; however, it is alsoconceivable that the flared or tapered section is not uniformly aroundthe circumference of the stent 10. For example, the stent 10 may have aflare only near the locations of the positioning arches 15 a, 15 b, 15c, wherein no flare is provided near the commissure regions, i.e. theregions in between the two arms 15 a′, 15 a″, 15 b′, 15 b″, 15 c′, 15 c″of two neighboring positioning arches 15 a, 15 b, 15 c.

As depicted in FIGS. 20b and 20c , the stent 10 according to thenineteenth embodiment comprises a continuous design of its lower endsection 2. Due to this continuous design, in the implanted and expandedstate of the stent 10, via the lower end section 2 of the stent 10 anuniform radial force is applied to the wall of the blood vessel intowhich the stent 10 is deployed.

If the implanted and expanded stent together with a valvular prosthesisaffixed thereto extend too far below the annulus of the heart there maybe the risk that the implanted endoprosthesis consisting of the stentone the one hand and the valvular prosthesis on the other hand contactsthe nerve bundles and heart block. The nerve bundles may enter at alocation approximately 6 to 10 mm below the annulus of the heart.

In order to avoid that the lower end section 2 of the implanted stent 10may touch the atrioventricular node, the stent 10 pursuant to thenineteenth embodiment is provided with an annular collar 40 which isshortened in its length by having only a single row of cells. In thisregard, the total height of the stent 10 and thus the total height ofthe endoprosthesis 1 to be implanted into the body of the patient arereduced.

Moreover, in the programming process during which the shape of thedesired (expanded) stent structure is fixed, the supporting webs 41 ofthe annular collar 40 may be programmed so that—when the stent 10 of thenineteenth embodiment is in its expanded state—only the upper section ofthe annular collar 40 extends in a radial direction outside thecircumference of the stent 10, whereas the lower end section of theannular collar 40 bended relative to the upper section of the annularcollar 40 in the radial direction inside the circumference of the stent10. The lower end section of the annular collar 40 may be bended suchthat it extends, for example, approximately parallel to the longitudinaldirection L of the stent 10. In this way, an increased contact force(radial force) is applied by the upper section of the annular collar 40to the wall of the blood vessel into which the stent 10 is deployed,whereas the risk is reduced that the lower end section of the annularcollar 40 can tough the atrioventricular node.

It is important to note, that the stent 10 according to the nineteenthembodiment comprises a several number of notches 12 e uniformlydistributed around the lower end section of the annular collar 40. Thesenotches 12 e can be used for fixing a heart valve prosthesis (not shownin FIGS. 20b and 20c ) to the stent 10, which may reduce the risk of anaxial displacement of the heart valve prosthesis 100 relative to thestent 10. Since a plurality of notches 12 e are used as additionalfastening means it is possible to utilize the lower end sections ofevery supporting web 41 of the annular collar 40 for additionallyfastening a heart valve prosthesis to the stent 10. This appearsdirectly from the flat roll-out view pursuant to FIG. 20 a.

A comparison with, for example, the flat roll-out view pursuant to FIG.17a (seventeenth embodiment) illustrates directly that the provision ofeyelets 12 f at the lower end sections of every supporting web 41 of theannular collar 40 requires much more material for each eyelet 12 fcompared with the amount of material which is necessary for formingrespective notches 12 e. Since it is conceivable for the stent 10 toexhibit a structure integrally cut from a portion of tube, in particularfrom a metal tube, which incorporates all structural components of thestent 10, in particular the positioning arches 15 a, 15 b, 15 c, theretaining arches 16 a, 16 b, 16 c and the annular collar 40 with definedadditional fastening means at the lower end thereof, an elaboratecutting pattern for forming the design of the stent 10 from the originaltube portion is important. In particular, it must be taken into accountthat the structure of the stent 10 with all structural stent componentsmust be cut from the limited lateral area of the original tube portion.

Hence, by providing notches 12 e instead of eyelets 12 f as additionalfastening means at the lower end section of the annular collar 40, agreater number of notches 12 e compared with the number of eyelets 12 fcan be generated. In detail, according to the nineteenth embodiment, thelower end sections of every supporting web 41 of the annular collar 40is provided with a corresponding notch 12 e acting as additionalfastening means. In contrast, in the seventeenth and eighteenthembodiments only the lower end sections of every second supporting web41 of the annular collar 40 can be provided with a corresponding eyelet12 f acting as additional fastening means.

In this regard, the stent design according to the nineteenth embodimentdiffers from the stent design, for example, according to the eighteenthembodiment in that at the lower end section of every supporting web 41of the annular collar 40 an additional fastening means is provided. Thisis due to the fact that, in the nineteenth embodiment of the stent 10,notches 12 e are used as additional fastening means.

Hence, in the nineteenth embodiment, the additional fastening means tobe used for fixing a heart valve prosthesis to the stent 10 are moreuniformly distributed around the lower end section of the annular collar40, thereby providing a more uniform fixation of a heart valveprosthesis to the stent. Hence, the risk of an axial displacement of theheart valve prosthesis relative to the stent may be further reduced.Each individual notch 12 e provided at the lower end section of theannular collar 40 thereby serves to guide a thread or thin wire withwhich the tissue component(s) of the valvular prosthesis is affixed orsewn to the lower end section of the annular collar 40 of the stent 10.In detail, the means (thread or thin wire) provided for fastening thetissue component(s) of the valvular prosthesis to the lower end sectionof the annular collar 40 is guided by way of the notches 12 e so that alongitudinal displacement of the valvular prosthesis relative to thestent 10 is substantially minimized. This also allows exact positioningof the valvular prosthesis relative the stent 10.

Moreover, by using corresponding notches 12 e for the secure and definedfixing of the tissue component(s) of the valvular prosthesis to thelower end section of the annular collar 40 of the stent 10, the means(threads or thin wires) used to fasten the tissue component(s) to thestent 10 are effectively prevented from being squeezed and thus degradedwhen the stent 10 with the valvular prosthesis affixed thereto, i.e. theendoprosthesis 1, is compressed and brought into its collapsed shapesuch as to be ready for being inserted into a catheter system which isused for implanting the endoprosthesis 1. In this regard, the risk ofstructural deterioration in the threads or thin wires used to fasten thetissue component(s) of the valvular prosthesis 100 to the stent 10 isreduced.

The cross-sectional shape to the notches 12 e may be adapted to thecross-sectional shape of the thread or thin wire used to fasten thetissue component(s) of the valvular prosthesis 100. This allows fixingof the tissue component(s) of the valvular prosthesis 100 to the stent10 at a precise predefined position relative to the stent 10. Becausethe fastening holes 12 are adapted to the thickness and/or thecross-sectional shape of the thread or thin wire used to affix thevalvular prosthesis 100 to the stent 10, relative movement between thestent 10 and the tissue component(s) of the valvular prosthesis 100 dueto the peristaltic motion of the heart can be effectively prevented whenthe endoprosthesis 1 is implanted. In the fully expanded and implantedstate of the endoprosthesis 1, the tissue component(s) of the valvularprosthesis 100 is/are thus fastened to the stent 10 with minimal play,based on which friction-induced wear of the thread or thin wire used toaffix the valvular prosthesis is minimized. As shown in, for example, inFIG. 20a , the notches 12 e have a semi-circular cross-sectional shape.

As can be seen, in particular from FIGS. 20b to 20d , the stent 10according to the nineteenth embodiment of the invention may furthercomprise at least one radial arch 32 a, 32 b, 32 c which enables aparticularly secure anchoring of the stent 10 in the site ofimplantation in the heart and which is substantially circumferentiallyaligned with at least one of the plurality of positioning arches 15 a,15 b, 15 c. In addition to its radial arches 32 a, 32 b, 32 c, the stent10 is further provided with a total of three leaflet guard arches 50 a,50 b, 50 c, each comprising two leaflet guard arms. It can be seen fromthe flat roll-out view shown in FIG. 20a that, in the structure of thestent according to the nineteenth embodiment, a leaflet guard arch 50 a,50 b, 50 c is provided in between each positioning arch 15 a, 15 b, 15c. Hence, in the stent according to the twelfth embodiment, a leafletguard arch 50 a, 50 b, 50 c is allocated to each positioning arch 15 a,15 b, 15 c.

Referring to the flat roll-out view shown in FIG. 20a , the radialarches 32 a, 32 b, 32 c of the stent 10 according to the nineteenthembodiment extend from the leaflet guard arches 50 a, 50 b, 50 c towardsthe upper end 3 of the stent 10. As is shown most clearly in FIG. 20a ,the stent 10 has three radial arches 32 a, 32 b, 32 c, with each arch 32a, 32 b, 32 c located between the two arms of each leaflet guard arch 50a, 50 b, 50 c. Each radial arch 32 a, 32 b, 32 c has a shape that isroughly inverse to each positioning arch 15 a, 15 b, 15 c and extends inthe opposite direction to each one of the positioning arches 15 a, 15 b,15 c.

On the other hand, each leaflet guard arch 50 a, 50 b, 50 c has asubstantially U-shaped or V-shaped structure which is closed to thelower end 2 of stent. Again, each leaflet guard arch 50 a, 50 b, 50 chas a shape that is roughly similar to the shape of the positioning arch15 a, 15 b, 15 c in between the corresponding leaflet guard arch 50 a,50 b, 50 c is arranged. Furthermore, each leaflet guard arch 50 a, 50 b,50 c extends in the same direction as the positioning arch 15 a, 15 b,15 c.

In the stent design of the nineteenth embodiment, each arm of a leafletguard arch 50 a, 50 b, 50 c merges at about the mid-point of the lengthof an arm of a radial arch 32 a, 32 b, 32 c into the arm of an opposingradial arch 32 a, 32 b, 32 c. According to the stent design of thenineteenth embodiment, the leaflet guard arches 50 a, 50 b, 50 c projectin the longitudinal direction L of the stent and have a reduced lengthsuch that the positioning arches 15 a, 15 b, 15 c can deploy during theexpansion of the stent 10 and the leaflet guard arches 50 a, 50 b, 50 cdo not interfere during deployment.

The positioning arches 15 a, 15 b, 15 c disposed on the stent 10 andalso the retaining arches 16 a, 16 b, 16 c may be curved in convex andarched fashion in the direction to the lower end section of the stent;i.e. toward the lower end 2 of the stent, whereby such a rounded formmay reduce injuries to the artery as well as facilitate the unfoldingduring the self-expansion. Such a design may enable an easier insertionof the positioning arches 15 a, 15 b, 15 c into the pockets T of thenative cardiac valve without correspondingly injuring the neighboringtissue or blood vessels (cf. FIGS. 18a to 18c ).

Although not explicitly illustrated in the flat roll-out view accordingto FIG. 20a , in the programming process during which the shape of thedesired (expanded) stent structure is fixed, the leaflet guard arches 50a, 50 b, 50 c are preferably programmed so that they extend in a radialdirection outside the circumference of the stent 10 when the stent 10 ofthe nineteenth embodiment is in its expanded state. In this way, anincreased contact force can be applied to the leaflets H of the native(diseased) cardiac valve when the stent of the nineteenth embodiment isin its expanded and implanted state. This, in turn, allows an increasedsecurity in the fixing of the stent in situ.

When the stent is in its expanded and implanted state, the leaflet guardarches 50 a, 50 b, 50 c actively keep the diseased leaflets H, i.e. theleaflets of the native cardiac valve, from impinging the leaflet tissueof the valvular prosthesis 100 attached to the stent 10, when thepositioning arches 15 a, 15 b, 15 c are placed outside the nativeleaflets. In addition, the leaflet guard arches 50 a, 50 b, 50 c mayalso provide additional anchoring and securing against migration. Thisfeature may be unique compared to the cage known from the prior artstent designs which are not provided with positioning arches to push thediseased leaflets out of the way.

As can be seen from the roll-out view depicted in FIG. 20a , accordingto the stent design of the nineteenth embodiment, the two arms 32′, 32″of each radial arch 32 a, 32 b, 32 c are connected together at the upperend 3 of the stent 10 by means of a radiused connecting portion or head.This head is not only radiused but also widens at the tip so that thehead abuts against the interior wall of the vessel over as large acontact area as possible when the stent 10 is in its expanded andimplanted state. The heads of each radial arch 32 a, 32 b, 32 c may alsoserve as additional means by which the stent 10 may be retained in acatheter before and during implantation and/or to recapture the stentafter implantation.

In the programming process during which the shape of the desired(expanded) stent structure is fixed, the radial arches 32 a, 32 b, 32 care programmed so that they extend in a radial direction outside thecircumference of the stent 10 when the stent 10 is in its expandedstate. In this way an increased contact force can be applied to thevessel wall by the upper end region of the stent 10. This, in turn,allows an increased security in the fixing of the stent 10 in situ,thereby reducing the likelihood of migration of the stent 10. Therefore,in its expanded state, in addition to the clamping effect of thepositioning arches 15 a, 15 b, 15 c and in addition to the additionalanchoring obtainable by the leaflet guard arches 50 a, 50 b, 50 c, thestent 10 of the nineteenth embodiment is secured in place onimplantation via radial forces exerted by the retaining arches 16 a, 16b, 16 c, the auxiliary arches 18 a, 18 b, 18 c, the radial arches 32 a,32 b, 32 c, and the annular collar 40, all of which project outwards ina radial direction from the circumference of the stent 10.

It can be seen from the flat roll-out view shown in FIG. 20a that theradial arches 32 a, 32 b, 32 c do not project in the longitudinaldirection L of the stent 10 beyond the plane in which the catheterretaining means 23 or the fastening means with fastening eyelets 24 aresituated. This may ensure that the catheter retaining means 23 canco-operate with corresponding means within a suitable implantationcatheter without interference from the heads of the radial arches 32 a,32 b, 32 c. Indeed, as explained above, the heads themselves can be usedas additional catheter retaining means or additional means to effectexplanation of the stent 10.

In principle, the stent 10 may have more than three radial arches 32 inorder to increase the radial contact force further. It is also possibleto provide barb elements on all or some of the radial arches 32 a, 32 b,32 c, for example, to allow a still better anchoring of the stent 10 atthe implantation site.

Moreover, with respect to fixing the upper area 3 of stent 10 to thewall of the blood vessel into which the stent 10 is deployed, it wouldbe conceivable for the stent 10 to comprise barb members arranged, forexample, on the eyelets 24, the tips of the barbs pointing toward thelower end 2 of stent 10.

In addition, a liner or sheath, typically a fabric, polymeric orpericardial sheet, membrane, or the like, may be provided over at leasta portion of the exterior of the stent 10 to cover all or most of thesurface of the outside of the stent 10, extending from a location nearthe lower end section of the stent to a location near the upper endsection of the stent. The liner may be attached to the stent 10 at atleast one end, as well as at a plurality of locations between said endsthereby forming an exterior coverage. Such exterior coverage provides acircumferential seal against the inner wall of the blood vessel lumen inorder to inhibit leakage of blood flow between the stent 10 and theluminal wall thereby and to prevent a blood flow bypassing theendoprosthesis 1.

For example, the liner may be stitched or otherwise secured to the stent10 along a plurality of circumferentially spaced-apart axial lines. Suchattachment permits the liner to fold along a plurality of axial foldlines when the stent 10 is radially compressed. The liner will furtherbe able to open and conform to the luminal wall of the tubular frame asthe frame expands. Alternatively, the liner may heat welded, orultrasonically welded to the stent 10. The liner may be secured to theplurality of independent arches (positioning arches 15 a, 15 b, 15 c,retaining arches 16 a, 16 b, 16 c, auxiliary arches 18 a, 18 b, 18 c,leaflet guard arches 50 a, 50 b, 50 c) preferably along axial lines. Inaddition, the liner may be secured to the annular collar 40 provided atthe lower end section 2 of the stent 10. The liner will preferably becircumferentially sealed against the stent 10 at at least one end.

By covering at least a part of the outside surface of the stent 10 withthe liner or sheath, thrombogenicity of the endoprosthesis 1 resultingfrom exposed stent elements is greatly reduced or eliminated. Suchreduction of thrombogenicity is achieved while maintaining the benefitsof having a stent structure which is used for spreading up a valvularprosthesis 100 and for anchoring the valvular prosthesis 100 in place.

As already mentioned, the stent 10 can be compressed from a relaxed,large diameter configuration to a small diameter configuration tofacilitate introduction. It is necessary, of course, that the outerliner remain attached to the stent 10 both in its radially compressedconfiguration and in its expanded, relaxed configuration.

The liner is composed of pericardial material or conventional biologicalgraft materials, such as polyesters, polytetrafluoroethylenes (PTFE's),polyurethanes, and the like, usually being in the form of woven fabrics,non-woven fabrics, polymeric sheets, membranes, and the like. Apresently preferred fabric liner material is a plain woven polyester,such as Dacron® yarn (Dupont, Wilmington, Del.).

A twentieth embodiment of the stent 10 according to the presentinvention is described in the following with reference to FIG. 21 whichis a flat roll-out view of this embodiment, whereby the cardiac valvestent 10 is shown in its expanded state.

The twentieth embodiment of the stent 10 is similar in structure andfunction with respect to the nineteenth embodiment. To avoid repetition,reference is therefore made to the above description of the nineteenthembodiment. In particular, the lower end section of the stent 10 isconstituted by an annular collar 40 which is likewise provided withnotches 12 e acting as additional fastening means.

In addition, the stent 10 according to the twentieth embodiment isprovided with retaining arches 16 a, 16 b, 16 c whose arms 16 a′, 16 a″,16 b′, 16 b″, 16 c′, 16 c″ are segmented by a plurality of bending edges33 which are not only used for defining a bending point of twoneighboring arm segments, but also as fastening notches which can beused for fixing a heart valve prosthesis to the stent 10.

The twentieth embodiment of the stent 10 also includes radial arches 32a, 32 b, 32 c extending from the positioning arches 15 a, 15 b, 15 ctowards the upper end 3 of the stent 10. As is shown in the FIG. 21, thestent 10 has three radial arches 32 a, 32 b, 32 c, with each arch 32 a,32 b, 32 c located between the two arms 15 a, 15 a′, 15 b, 15 b′, 15 c,15 c′ of each positioning arch 15 a, 15 b, 15 c. Each radial arch 32 a,32 b, 32 c has a shape that is roughly inverse to each positioning arch15 a, 15 b, 15 c and extends in the opposite direction to each one ofthe positioning arches 15 a, 15 b, 15 c.

Contrary to the stent design of the nineteenth embodiment, however, thestent design of the twentieth embodiment is not provided with leafletguard arches 50 a, 50 b, 50 c. Furthermore, each arm of a radial arch 32a, 32 b, 32 c merges at about the mid-point of the length of the stent10 into an arm 15 a′, 15 a″, 15 b′, 15 b″, 15 c′, 15 c″ of an opposingpositioning arch 15 a, 15 b, 15 c.

A twenty-first embodiment of the stent 10 according to the presentinvention is described in the following with reference to FIG. 22. Indetail, FIG. 22 is a flat roll-out view of the twenty-first embodiment,whereby the cardiac valve stent 10 is shown in its expanded state.

From a comparison of FIG. 22 with FIG. 20d it is derivable that thetwenty-first embodiment of the stent 10 is similar in structure andfunction with respect to the nineteenth embodiment. To avoid repetition,reference is therefore made to the above description of the nineteenthembodiment.

The twenty-first embodiment of the stent 10 only differs from thenineteenth embodiment in that the respective lower end sections of theleaflet guard arches 50 a, 50 b, 50 c are removed. In particular, thelower end sections of the leaflet guard arches 50 a, 50 b, 50 c betweenthe points where each arm of a radial arch 32 a, 32 b, 32 c merges isremoved.

The above disclosure is intended to be illustrative and not exhaustive.This description will suggest many variations and alternatives to one ofordinary skill in this art. All these alternatives and variations areintended to be included within the scope of the claims where the term“comprising” means “including, but not limited to”. Those familiar withthe art may recognize other equivalents to the specific embodimentsdescribed herein which equivalents are also intended to be encompassedby the claims.

Further, the particular features presented in the dependent claims canbe combined with each other in other manners within the scope of theinvention such that the invention should be recognized as alsospecifically directed to other embodiments having any other possiblecombination of the features of the dependent claims. For instance, forpurposes of claim publication, any dependent claim which follows shouldbe taken as alternatively written in a multiple dependent form from allprior claims which possess all antecedents referenced in such dependentclaim if such multiple dependent format is an accepted format within thejurisdiction (e.g. each claim depending directly from claim 1 should bealternatively taken as depending from all previous claims). Injurisdictions where multiple dependent claim formats are restricted, thefollowing dependent claims should each be also taken as alternativelywritten in each singly dependent claim format which creates a dependencyfrom a prior antecedent-possessing claim other than the specific claimlisted in such dependent claim below.

What is claimed is:
 1. A method of placing an implant comprising a stentat a native heart valve site, the method comprising: orienting anexpandable body of the stent such that a first open end of the stent isupstream a second open end of the stent relative to a direction of bloodflow through a native heart valve, the native heart valve comprisingnative leaflets and an annulus; radially expanding a plurality ofpositioning arches positioned around an outer perimeter of theexpandable body; inserting the plurality of positioning archesrespectively within a plurality of pockets defined by the nativeleaflets and a heart structure from which the native leaflets extend;and radially expanding the first open end of the stent into a positionupstream of the annulus and out of contact with nerve bundles.
 2. Themethod of claim 1, wherein radially expanding the first open end intothe position upstream of the annulus comprises radially expanding thefirst open end into a position that is less than about 10 mm upstreamfrom the annulus.
 3. The method of claim 1, wherein radially expandingthe first open end into the position upstream of the annulus comprisesradially expanding the first open end into a position that is less thanabout 6 mm upstream from the annulus.
 4. The method of claim 1, whereinradially expanding the first open end comprises radially expanding aplurality of retaining arches into contact with a vascular wall.
 5. Themethod of claim 4, wherein radially expanding the plurality of retainingarches comprises positioning the native leaflets between the pluralityof positioning arches and the plurality of retaining arches.
 6. Themethod of claim 1, wherein radially expanding the first open endcomprises radially expanding an annular collar into contact with avascular wall.
 7. The method of claim 6, wherein radially expanding theannular collar comprises radially expanding at least one row of closedcells, the closed cells being circumferentially disposed around alongitudinal axis of the stent.
 8. The method of claim 1, wherein thenative heart valve is an aortic valve and the native leaflets are aorticcusps, and wherein inserting the plurality of positioning archesrespectively within the plurality of pockets comprises contactingoutflow surfaces of the aortic cusps with the plurality of positioningarches.
 9. The method of claim 1, wherein radially expanding theplurality of positioning arches comprises radially expanding threepositioning arches.
 10. The method of claim 9, wherein inserting theplurality of positioning arches respectively within the plurality ofpockets comprises inserting each of the three positioning arches withina respective pocket defined by one of the native leaflets and the heartstructure from which the native leaflet extends.
 11. The method of claim1, wherein radially expanding the first open end of the stent comprisesradially expanding the first open end to a diameter ranging from about22 mm to about 33 mm.
 12. A method of placing an implant comprising astent at a native heart valve site, the method comprising: orienting anexpandable body of the stent such that a first stent segment of thestent is upstream of a second stent segment of the stent relative to adirection of blood flow through a native heart valve, the native heartvalve comprising native leaflets and an annulus; aligning regions of thesecond stent segment having a first strut density with respectivecommissures of the native heart valve; and aligning regions of thesecond stent segment having a second strut density with respective cuspsof the native heart valve, wherein the first strut density is differentthan the second strut density.
 13. The method of claim 12, wherein thefirst strut density is higher than the second strut density.
 14. Themethod of claim 12, further comprising radially expanding the firststent segment against a vascular wall of the native heart valve site.15. The method of claim 12, further comprising radially expanding aninflow end of the stent more than an oppositely disposed, outflow end ofthe stent.
 16. The method of claim 15, wherein radially expanding theinflow end of the stent comprises radially expanding the inflow end ofthe stent to a diameter ranging from about 22 mm to about 33 mm.
 17. Themethod of claim 12, wherein the implant comprises a valvular prosthesiscarried by the stent, the valvular prosthesis comprising a plurality ofprosthetic valve leaflets attached to the stent and further comprising:locating the regions of the second stent segment having the first strutdensity on an inflow side of the valvular prosthesis; and locating theregions of the second stent segment having the second strut density onan outflow side of the valvular prosthesis.
 18. The method of claim 12,further comprising: applying a first radial force against a firstportion of a vascular wall with the first stent segment; and applying asecond radial force against a second portion of the vascular wall withthe second stent segment, wherein the first radial force is greater thanthe second radial force.
 19. The method of claim 18, wherein applyingthe first radial force comprises uniformly distributing the first radialforce along the first portion of the vascular wall via a plurality ofclosed cell structures of the first stent segment.
 20. The method ofclaim 12, wherein aligning the regions of the second stent segmenthaving the first strut density with the respective commissures of thenative heart valve comprises minimizing blood leakage through the nativeheart valve.